HYDRO  -ELECTRI  c 


VON  SCHON 


LIBRARY 

OF  THE 

UNIVERSITY  OF  CALIFORNIA. 


Class 


HYDRO-ELECTRIC 
PRACTICE 

A    PRACTICAL    MANUAL    OF   THE    DEVELOPMENT    OF  WATER 

POWER,  ITS  CONVERSION  TO  ELECTRIC  ENERGY, 

AND  ITS  DISTANT  TRANSMISSION 


BY 


H.  A.  E.  C.  VON   SCHON 


It 

CIVIL  AND   HYDRAULIC  ENGINEER;    MEMBER   OF   THE  AMERICAN  SOCIETY   OF  CIVIL   ENGINEERS 


PHILADELPHIA   &f  LONDON 

J.   B.   LIPPINCOTT    COMPANY 

1908 


08\ 
S3 


COPYRIGPT,  1908 
BY  J.  B.  LIPPINCOTT  COMPANY 


Printed  by  J.  B.  Lippincoll  Company 
The  Washington  Square  Press,  Philadelphia,  U.  S,  A. 


PREFACE 

THE  economical  transmission  of  electric  energy  to  distances  great 
and  small,  the  rapidly  increasing  utilization  of  electro-motive  power  in 
industrial  establishments,  and  the  advent  of  the  electric  interurban  rail- 
roads are  responsible  for  the  marked  movement  of  impressing  water- 
powers  to  the  service  of  generating  electric  current;  and  now  water- 
power,  which  had  been  almost  relegated  to  obscurity  by  the  perfection 
of  the  steam-engine,  is  not  only  regaining  but  even  exceeding  its  former 
importance  as  an  economical  prime  power  source. 

It  is  entirely  within  the  facts  to  state  that  a  normally  conditioned 
hydro-electric  power  plant  can  successfully  compete  with  the  most 
refined  steam-power  plant  and  the  lowest  priced  fuel,  natural  gas. 

No  wonder  then  that  water-powers  are  to-day  being  sought  after 
with  feverish  activity,  and  that  some  remarkable  successes  have  been 
achieved,  but  also  that  many  disastrous  failures  must  be  recorded. 

Hydro-electric  power  development  is  a  much  more  complex  under- 
taking than  a  large  majority  of  the  promoters  of  such  enterprises  realize 
when  the  subject  is  first  approached,  but  which  is  most  forcibly  impressed 
upon  them  when  the  carrying  out  of  the  project  is  seriously  attempted. 
Unfortunately,  the  most  dangerous  pitfalls  are  encountered  at  the 
beginning  of  the  undertaking,  and  unless  these  are  properly  guarded 
against  the  finished  work  may  disclose  some  incurable  defects. 

Developments  of  the  important  natural  resources  of  mines,  of  forests, 
and  of  manufacturing  and  transportation  projects  are  rarely  undertaken 
except  upon  the  findings  of  recognized  authorities  on  these  respective 
subjects;  not  so,  however,  with  hydro-electric  power  propositions,  which 
are  most  frequently  begun  in  a  hap-hazard  sort  of  fashion,  with  the 
stream  and  a  fall  as  assumed  assets,  while  the  market,  constancy  of 
output,  cost  of  product,  riparian  rights,  and  numerous  other  controlling 
features  remain  undetermined  until  some  later  day.  Hence  promoters 
of  hydro-electric  projects  have  not  found  the  investing  public  at  all 
eager  to  take  their  securities,  because  of  the  general  and  well-grounded 
impression  that  their  presentations  are  not  entitled  to  the  same  degree 


174385 


iv  PREFACE 

of  confidence  as  other  undertakings  command,  nor  can  there  be  any 
hope  for  a  tide  in  their  favor  until  such  confidence  be  inspired. 

Publicity  of  the  realities  of  a  subject  will  always  carry  conviction 
of  merit,  if  such  there  be;  and  much  of  the  reluctance  of  capital  to 
recognize  the  indubitable  value  of  investments  in  hydro-electric  power 
plants  is  no  doubt  due  to  the  paucity  of  the  proper  sort  of  educating 
literature  on  this  subject. 

This  at  least  is  the  judgment  of  the  author,  born  of  the  experience 
gained  by  some  fifteen  years  of  exclusive  hydro-electric  power  practice, 
and  this  is  the  reason  and  purpose  of  this  volume, — to  place  within 
reach  of  the  promoter,  investor,  and  practitioner  an  analytical  treat- 
ment of  hydro-electric  practice  in  all  its  phases  from  inception  to 
realization. 

This  subject  is  treated  in  two  parts;  the  first  is  entitled  " Analysis 
of  a  Hydro-electric  Project,"  and  is  written  for  the  layman,  being  devoid 
of  technical  treatment,  and  may  therefore  be  characterized  as  the  com- 
mercial essence  of  the  subject.  The  author  believes  that  an  intelligent 
perusal  of  this  first  part  will  insure  the  reader  against  those  errors  of 
commission  and  omission  which  cause  most  of  the  failures  in  these  proj- 
ects. No  engineering  training  or  experience  is  required  clearly  to  follow 
and  fully  to  appreciate  and  understand  the  presentation  of  the  analysis, 
which  covers  the  topic  as  completely  as  can  be  done  without  the  intro- 
duction of  the  technic. 

CHAPTER  I.  treats  of  the  market  of  electric  current,  where  it  may 
be  found  and  how  its  value  is  readily  determined.  This  is  purely  a 
commercial  subject  and  ranks  first  in  importance  in  the  analysis. 

CHAPTER  II.  discusses  the  power  opportunity,  how  the  available 
flow  can  be  ascertained  and  the  fall,  and  from  these  the  power  output  on 
which  the  project  may  be  safely  based. 

CHAPTER  III.  relates  to  the  feasibility  and  practicability  of  the 
development.  It  treats  of  questions  of  riparian  rights,  Federal  and 
State  control  of  streams,  economical  limitations  and  of  the  investment 
balance. 

CHAPTER  IV.  gives  a  non-technical  synopsis  of  the  cost  of  such  a 
project,  with  general  reference  to  the  separate  features  of  the  required 
works  and  equipment;  and 

CHAPTER  V.,  which  closes  the  analysis,  reviews  the  value  of  the 
project  as  an  investment  and  suggests  its  proper  presentation. 


PREFACE  v 

In  this  part  are  incorporated  sixteen  diagrams,  from  which  the 
reciprocals  of  hydraulic,  mechanical,  and  electrical  power,  horse-power 
and  kilowatts,  the  flow  over  spillways  and  from  reservoirs,  fixed  charges 
of  and  revenues  from  hydro-electric  plants,  and  the  approximate  quan- 
tities for  dams,  foundations,  power  houses,  embankments,  bulkheads, 
and  transmission  lines  may  be  readily  ascertained.  Other  subjects, 
such  as  drainage  areas,  precipitation  belts,  and  report  and  plans,  are 
suitably  illustrated. 

PART  II.,  "Designing  and  Equipping  the  Plant,"  is  written  for  the 
student  and  practitioner.  The  arrangement  is  in  the  logical  sequence 
of  the  pursuance  of  the  plan.  The  aim  of  the  author  has  been  to  render 
the  treatment  complete  in  all  its  phases,  with  the  exception  of  presup- 
posing a  knowledge  of  the  principles  of  surveying  and  the  rudiments  of 
hydraulics,  hydrostatics,  and  dynamics. 

Each  subject  involving  static  or  dynamic  principles  is  analyzed 
from  its  basic  functions,  and  all  formulas  are  developed  in  elementary 
progression;  wherever  practicable  without  complexity  of  methods  or 
deductions,  the  useful  constants  are  reduced  to  diagrammatical  forms, 
which  become  available  for  ready  reference  in  application.  All  features 
of  importance  are  illustrated  by  sketches  or  views  from  existing  plants, 
chiefly  such  as  have  been  designed  and  constructed  by  the  author,  and 
the  quantities  of  materials  for  all  structures  are  given,  for  useful  units, 
in  tables  or  diagrams. 

CHAPTER  VI.  treats  of  the  surveys,  embracing  examination  of  maps, 
reconnaissance,  topographic,  stadia  and  photo-topographic  operations, 
triangulation  and  levelling,  flow  measurements  by  different  methods 
and  deductions  of  run-off  from  precipitation  and  evaporation. 

CHAPTER  VII.  deals  with  development  programmes.  This  discussion 
covers  the  many  possibilities  presented  by  various  conditions,  with 
illustrated  examples  of  the  most  important  and  frequent  occurrences. 

CHAPTER  VIII.  embraces  structural  types,  beginning  with  definition 
of  terms  and  methods,  including  the  theory  and  constants  of  concrete-steel 
construction,  methods  of  coffering  preparatory  to  dam  and  power-house 
construction,  with  tables  of  quantities  for  dikes,  cribs,  sheet  pile  and  wall 
curtains,  and  the  various  types  of  cut-off  structures. 

The  treatment  of  dams  and  spillways  is  introduced  by  an  exhaustive 
analysis  of  the  basic  theories  of  pressure  and  resistance  and  of  all  the 
underlying  principles,  with  original  determinations  of  practical  constants 


vi  PREFACE 

for  a  variety  of  designs,  and  their  detailed  parts,  such  as  foundation, 
substructures  and  superstructures,  and  appurtenant  features.  The  vari- 
ous phenomena  influencing  the  design  of  dams,  such  as  overflow,  back- 
swell,  and  the  control  of  flood  discharge,  are  fully  analyzed.  Especial 
attention  has  been  given  to  this  topic  of  dam  designs;  it  is  rudimentary 
from  start  to  finish,  with  some  original  conclusions,  it  is  believed. 

The  concrete-steel  gravity  dam  design  is  fully  detailed  as  to  theory 
and  practical  execution;  so  are  several  types  of  the  open  spillway, 
flashboards,  sluices,  gates,  fishways,  and  log  chutes.  Timber  spillways 
are  likewise  treated,  with  stability  discussion  and  quantity  tables.  The 
retaining  wall  theory  is  presented  in  connection  with  abutments,  as  are 
embankments,  bulkheads,  and  reservoir  structures  of  various  forms. 

Diversion  works  embrace  open  channels,  flumes,  pipe  lines  of  con- 
crete, steel  plate  and  wood  stave,  with  theories  of  flow,  slope,  and 
velocities  fully  analyzed  and  development  of  practical  constants  tabu- 
lated for  all  the  different  ranges  entering  this  subject. 

Power  station  follows,  with  all  the  practicable  variations  fully 
illustrated  and  described  and  with  tabulated  quantities.  This  subject 
is  treated  also  in  detail  of  foundation,  pits,  penstocks,  and  operating 
floor,  and  considerable  space  is  devoted  to  their  full  description  and 
to  illustration  of  existing  plants.  The  submerged  power  station,  which 
represents  the  most  recent  developments  in  hydro-electric  practice, — 
that  is,  the  location  of  all  power  equipment  in  the  interior  of  a  hollow 
concrete-steel  spillway, — is  described  and  profusely  illustrated  by  views 
of  the  first  of  this  kind  of  plant  recently  completed. 

CHAPTER  IX.  treats  of  the  power  equipment,  with  theory  of  turbine 
designs  and  efficiencies,  dimensions  and  output  constants,  the  latter 
being  reduced  to  diagrams.  This  treatment  of  turbines  has  been  compiled 
with  especial  care,  for  the  purpose  of  conveying  a  clear  conception  of 
this  most  important  topic  of  hydro-electric  practice.  Hydraulic  gov- 
ernors are  also  described  and  illustrated. 

Electric  equipment  follows,  with  a  brief  treatment  of  the  magneto- 
electric  theories,  current  symptoms,  design  and  efficiencies  of  dynamos 
and  their  regulation.  Dimensions  and  output  of  generators  are  reduced 
to  diagrams.  Transmission  of  electric  current  is  introduced  by  an  ana- 
lytical theory  of  current  transformation  and  conversion,  determination 
of-  line  capacity,  and  the  designs  of  line  supports,  wire  fastenings,  and 
insulators. 


PREFACE  vii 

CHAPTER  X.  closes  Part  II.  with  a  brief  generalization  on  the  prepa- 
ration of  plans,  estimates,  specifications,  and  of  the  engineering  control 
of  constructions. 

The  author  fully  realizes  that  many  features  relating  to  hydro- 
electric practice  are  herein  treated  on  the  surface  only,  and  he  hopes  to 
present  them  in  exhaustive  detail  in  a  future  work.  This  refers  princi- 
pally to  the  maintenance  and  operation  of  hydro-electric  power  plants 
and  such  detail  subjects  as  the  operation  of  the  generating,  transmis- 
sion, and  distributing  plants,  with  chapters  on  underwashing  of  founda- 
tions, embankments,  and  retaining  walls,  and  repair  methods;  flood 
rises,  head  fluctuations,  anchor  and  slush  ice  formation  and  practical 
safeguards;  trash-rack  functions,  gate  operations,  pipe-line  defects, 
maintenance  and  repairs;  turbine  regulation  and  management;  electric 
generating  plant  phenomena  and  their  practical  solution;  transmission 
accidents  and  remedies;  substation  practice  for  lighting,  industrial, 
and  traction  power  and  electric  heating  service;  commercial  rates  and 
business  management;  valuations  of  various  electric  properties,  such 
as  light  plants  and  railroads,  and  statistical  facts  of  operating  costs 
and  earnings  compiled  from  existing  plants  located  in  various  sections 
and  of  different  capacities. 

The  author  has  drawn  freely  upon  standard  works  for  the  various 
topics  covered  by  this  subject,  especially  Hydraulics  and  Water  Supply, 
by  J.  T.  Fanning,  C.E.,  Hydraulics,  by  M.  Merriman,  C.E.,  Hydraulics 
and  Hydraulic  Motors,  by  Julius  Weisbach,  Ph.D.,  Hydraulic  Motors, 
by  G.  R.  Bodmer,  A.M.,  Electric  Motors,  by  S.  P.  Thompson,  D.S.C., 
and  Electric  Transmission,  by  Louis  Bell,  Ph.D. 

In  closing,  the  author  wishes  to  give  expression  of  his  full  apprecia- 
tion of  the  services  rendered  by  Mr.  K.  Asker,  C.E.,  who  prepared  all 

the  drawings. 

H.  A.  E.  C.  VON  SCHON. 

DETROIT,  MICH.,  June,  1908. 


TABLE   OF   CONTENTS 


PART  I. 

ANALYSIS    OF    A    HYDRO-ELECTRIC    PROJECT 

CHAPTER  I.  PAGE 

THE  MARKET 1 

Article      1.  Lighting  Service 1 

Article      2.  Industrial  Service 2 

Article      3.  Special  Service 4 

Article      4.  Traction  Service 4 

Article      5.  Highest  Remunerative  Service 4 

Article      6.  Current  Market  Analysis 4 

CHAPTER  II. 

POWER  OPPORTUNITY 8 

Article      7.  The  Flow 8 

Article      8.  Drainage  Area 9 

Article      9.  Drainage  Area,  Topography 26 

Article    10.  Drainage  Area,  Geology 27 

Article    1 1 .  Drainage  Area,  Flora  and  Culture 28 

Article    12.  Precipitation 29 

Article    13.  Stream  Flow,  Determination 30 

Article    14.  Evaporation 32 

Article    15.  Flow  Deduction 36 

Article    16.  Flow  Measurements 37 

Article    17.  Fall,  Available 40 

Article    18.  Power  Output 40 

CHAPTER  III. 

FEASIBILITY  AND  PRACTICABILITY 47 

Article    19.  Government  Control 47 

Article    20.  Riparian  Titles 53 

Article    21.  Practicability  of  Development 54 

Article    22.  Investment  Balance 55 

CHAPTER  IV. 

COST  OF  DEVELOPMENT 61 

Article    23.  Cost  of  Dam 61 

Article    24.  Cost  of  Diversion  Works 67 

Article    25.  Cost  of  Power  House 67 

Article    26.  Cost  of  Reservoir  Embankments 68 

Article    27.  Cost  of  Power  Equipment 70 

Article    28.  Cost  of  Transmission  Line 70 

Article    29.  Cost  of  Development 74 

ix 


x  TABLE   OF   CONTENTS 

CHAPTER  V.  PAGB 

VALUE  OF  PROJECT  AND  PRESENTATION 75 

Article    30.  Report  on  a  Hydro-electric  Project 75 

Article    31.  Value  of  a  Hydro-electric  Opportunity 88 


PART  II. 

DESIGNING    AND    CONSTRUCTING    THE   DEVELOPMENT 

CHAPTER  VI. 

THE  SURVEY 90 

Article    32.  Examination  of  Maps 90 

Article    33.  Reconnaissance 91 

Article    34.  Triangulation • 92 

Article    35.  Elevations 93 

Article    36.  Topography 94 

Article    37.  Phototopography 94 

Article    38.  Detail  Surveys 99 

Article    39.  Borings 100 

Article    40.  Stream  Gaugings 100 

Article    41.  Stream  Gaugings,  Reductions 103 

Article    42.  Stream  Discharge  Curve 103 

Article    43.  Weir  Measurement 107 

Article    44.  Flow  Deduced  from  Precipitation  and  Evaporation 108 

Article    45.  A  Typical  Case  of  Flow  Determination 109 

Article    46.  Reservoir  Sites 115 

Article    47.  Floating  Timber 115 

CHAPTER  VII. 

DEVELOPMENT  PROGRAMME 116 

Article    48.  The  Direct  Development 116 

Article    49.  The  Short  Diversion  Programme 117 

Article    50.  The  Distant  Diversion  Programme 117 

Article    51.  Development  Scope 129 

CHAPTER  VIII. 

STRUCTURAL  TYPES 131 

Article    52.  Foundation  Function 131 

Article    53.  Terms,  Materials,  and  Methods 135 

Article    54.  Coffering 143 

Article    55.  Foundation  Design 144 

Article    56.  Foundation  Construction 147 

Article    57.  Superstructure 148 

Article    58.  The  Length  of  Spillway 159 

Article    59.  Pressure  and  Resistance 160 

Article    60.  Sliding  of  Spillway 169 

Article    61.  Overturning  of  Spillway 170 

Article    62.  Crushing  or  Rupturing  of  Spillway 170 

Article    63.  Safety  Factor  in  Spillway  Design 174 

Article    64.  Spillway  Design,  Theoretical 176 

Article    65.  Spillway  Design,  Practical 180 


TABLE    OF   CONTENTS 


XI 


Article    66.  Spillway  Crest,  Shape  of 185 

Article    67.  Gravity  Spillways 186 

Article    68.  Open  Spillway 194 

Article    69.  Determining  the  Spillway  Type 202 

Article    70.  Timber  Spillways 205 

Article    71.  Spillway  to  Part  Height 209 

Article    72.  Abutments  of  Spillway 209 

Article    73.  Reservoir  Dams 221 

Article    74.  Appurtenances  of  Spillways  and  Dams 227 

Article    75.  Diversion  Works 235 

Article    76.  Power  House 254 

Article    77.  Appurtenances  to  the  Power  House 264 

Article    78.  Submerged  Power-House  Design 266 

CHAPTER  IX. 

EQUIPMENT • 276 

Article    79.  Hydraulic  Equipment,  Theory 276 

Article    80.  Classification  of  Turbines 285 

Article    81.  Mixed  Flow  Reaction  Turbine,  Description 287 

Article    82.  Central  Discharge  Reaction  Turbine,  Description 294 

Article    83.  American  Impulse  Turbine,  Description 296 

Article    84.  Draft  Tube  Theory 296 

Article    85.  Turbine  Efficiency,  Theory  of  Deduction 298 

Article    86.  Typical  Turbine  Installations 300 

Article    87.  Reaction  Turbine  Output 314 

Article    88.  Reaction  Turbine  Design 318 

Article    89.  Output  of  Tangential  Impulse  Turbine 320 

Article    90.  Turbine  Output  Constants,  Summary  of 322 

Article    91.  Turbine  Equipment,  Determining  Same 322 

Article    92.  Turbine  Governors 326 

Article    93.  Electric  Equipment,  Magneto-dynamic  Theory 330 

Article    94.  Some  Current  Symptoms 333 

Article    95.  Dynamo  Parts,  their  Purpose  and  Design 337 

Article    96.  Current  Reorganization 342 

Article    97.  Current  Transformation 343 

Article    98.  Current  Transmission 345 

Article    99.  Current  Regulation 348 

Article  100.  Electric  Generating  Plant 350 

Article  101.  Transmission  Plant,  Equipment 358 

Article  102.  Auxiliary  Power  Plant 364 

CHAPTER  X. 

CONSTRUCTING  THE  PLANT ., 368 

Article  103.  Plans 368 

Article  104.  Estimates 369 

Article  105.  Specifications 369 

Article  106,  Engineering  Control 371 


xii  TABLE    OF   CONTENTS 

TABLES.  PAGE 

1 .  Drainage  Areas  and  Low  Monthly  Flow 10 

2.  Evaporation  from  Water  Surface 33 

3.  Watercourses  under  Government  Control 50 

4.  Concrete  Characteristics 140 

5.  Reinforcing  Steel  Characteristics ; 141 

6.  Concrete-Steel  Beams 141 

7.  Values  for  Concrete-Steel  Beam  Designs 141 

8.  Coffer  Structures,  Quantities 144 

9.  Cut-off  Walls,  Quantities 147 

10.  Characteristics  of  Normal  Solid  Spillway  Section 185 

11.  Gravity  Spillway,  Bending  Moments 191 

12.  Gravity  Spillway,  Dimensions 192 

13.  Gravity  Spillway,  Material  Bill 192 

14.  Gravity  Spillway,  Characteristics  of  Design 194 

15.  Timber  Spillway,  Quantities 208 

16-24.  Flow  in  Open  Channels,  Characteristics 238-241 

25-29.  Flow  in  Pipes,  Characteristics 249-251 

30.  Permeability  of  Field  Magnet  Metal 339 

31.  Copper  Wire  Characteristics 340 

32.  Standard  Generators,  Characteristics 355 

33.  Aluminum  Wire,  Characteristics 359 


LIST   OF   ILLUSTRATIONS 


CHARTS  PAGE 

1.  Drainage  Area  of  Green  River,  Ky.,  above  Glenmore 11 

2.  Cumberland  River  Drainage  Area  above  Nashville,  Tenn 29 

3.  General  Distribution  of  Precipitation 30 

DIAGRAMS 

1.  Horse-power  and  Kilowatts ' 3 

2.  Discharge  over  Flat-crested  Spillway 39 

3.  Water-power  and  Electric  Power 43 

4.  Continuous  Flow  from  Reservoirs 45 

5.  Fixed  Charges  for  Plants  of  500-1000  H.  P 57 

6.  Fixed  Charges  for  Plants  of  1000-5000  H.  P 58 

7.  Fixed  Charges  for  Plants  of  5000-10,000  H.  P 59 

8.  Current  Rates  for  Horse-power  and  Kilowatt 60 

9.  Masonry  Dams,  Dimensions  and  Quantities 63 

10.  Concrete-steel  Dams,  Quantities 64 

11.  Cost  of  Concrete 65 

12.  Dam  Foundation  and  Abutment  Quantities 66 

13.  Power  House,  Quantities 69 

14.  Earth  Embankment,  Quantities 71 

15.  Reservoir  Bulkhead,  Quantities 72 

16.  Transmission  Line,  Weight  of  Line  Wire 73 

17.  Surface  to  Mean  Velocity >  •  104 

18.  Rod  to  Mean  Velocity 105 

19.  Typical  Discharge  Curve 106 

20-25.  Backswell,  Slope 152-157 

26-29.  Pressure  Moment,  Solid  Spillway 165-168. 

30.  Comparative  Cost  of  Timber  and  Concrete  Spillway 211 

31-33.  Retaining  Wall,  Pressure  Moments , 215-217 

34.  Vertical  Turbines,  Cased;  Dimensions  of 303 

35.  Horizontal  Turbines,  Drowned,  Dimensions  of 307 

36.  Single  Horizontal  Turbines,  Drowned,  Dimensions  of 311 

37.  Horizontal  Turbines,  Cased,  Dimensions  of 317 

38.  Reaction  Turbines,  Maximum  Efficiency  Output 319 

39.  Tangential  Impulse  Turbine,  Maximum  Efficiency  Output 323 

40.  Generator  Dimensions 357 

FIGURES 

1.  Base  Benches;   Base  Supporting  Brackets 92 

2.  Tripod  and  Target 93 

3-6.  Phototopography 94 

7.  Detail  Surveys ;  .  . .  .  99 

8.  Borings  to  ascertain  Character  of  Soil  at  Sites  of  Dam,  Diversion  Works,  etc 100 

9-11.  Stream  Gaugings 101 

xiii 


xiv  LIST  OF  ILLUSTRATIONS 

FIG-  PAGE 

12-  Dike 135 

13.  Timber  Sheet 136 

14.  Steel  Piling 13g 

15.  16.  Log  Crib  and  Timber  Crib 137 

17.  Concrete  Piles 138 

18.  Triple-lap  Sheet  Pile 139 

19.  Sheet  Pile  Dike 143 

20^1.  Spillway  Sections • 161-183 

42.  Solid  Spillway,  Crest  and  Toe 187 

43-45.  Diagrams  illustrating  Pressure  and  Resistance  Factor 189,  190 

46.  Gravity  Spillway 193 

47-49,  55.  Overflow  and  Underflow  Sluices 195}  197  f  200 

50-54.  Stop-logs,  Needles,  Valves,  Gates,  and  Shutters 197-200 

56.  Movable  Wier 202 

57.  Timber  Spillways 207 

58-61.  Spillway  Abutments  (Diagrams) 210-212 

62.  Retaining  Crib 213 

63.  Gravity  Retaining  Wall 21e 

64.  65.  Concrete  Steel  Retaining  Wail 219  220 

66.  Reservoir  Embankment 223 

67.  Reservoir  Bulkhead 225 

68-71.  Discharge  through  Submerged  Orifices 227-229 

72.  Fish-ladders 232 

73.  Flashboards 233 

74.  Wells  and  Galleries  in  Solid  Spillways 235 

•  75-77.  Diversion  Canals 236  245 

78.  Canal  Headgate 247 

79.  Flumes  and  Trestles 249 

80.  Pipe  Line  and  Details 253 

81.  Intake  Gate  Valve  and  Trash  Rack 254 

82.  Power-house  Substructure 256 

83.  Power-house  Turbine  Bays 257 

84.  Power-house,  Low  Head,  Vertical  Turbines,  Drowned . 259 

85.  Power-house,  Low  Head,  Horizontal  Turbines,  Drowned  in  Forebay 261 

86.  Power  House  for  Low  Head  and  Horizontal  Turbines,  Drowned 262 

87.  Power  House,  Fluctuating  Head,  Serial  Turbines 263 

88.  Power  House  for  Low  Head  and  Double  Vertical  Turbines,  Drowned 265 

89.  Power  House,  Medium  Head,  Horizontal  Turbines,  Cased ; . . .  267 

90.  Trash  Rack  and  Details 268 

91.  Power  Spillway 271 

92-101.  Hydro-dynamic  Energy  (Diagrams) 281-285 

102-106.  Reaction  Turbine  Runner 288 

107.  Wicket-Gate  Guide-Wheel 288 

108.  Sections  of  Guide-Vanes  and  Shutters 289 

109.  Reaction  Turbine,  Wicket  Gate 291 

110.  Reaction  Turbine,  Cylinder  Gate 293 

111.  Double  Turbine  Draft-Chest 294 

112.  Assembled  Twin  Turbines 294 

113.  Reaction  Turbine  for  High  Head 295 

114.  Impulse  Wheel 297 

115.  Vertical  Turbines,  Paired  and  Drowned,  Geared  Connections 302 

116.  Vertical  Turbines,  Paired  and  Cased,  Geared  Connections 305 

117.  Horizontal  Turbines,  Paired  and  Drowned 306 


LIST  OF  ILLUSTRATIONS  xv 

FIG.  PAGE 

118.  Horizontal  Turbines,  Three  in  Line,  Drowned 309 

119.  Horizontal  Turbines,  Four  in  Line,  Drowned 312 

120.  Horizontal  Turbines,  Paired,  Cased,  with  Top  or  Side  Supply 313 

121.  Horizontal  Turbine,  Cased,  with  End  Supply 315 

122.  Lombard  Governor 326 

123.  Sturgess  Governor 327 

124.  Woodward  Governor 328 

125.  Lombard-Replogle  Governor 329 

126.  127.  Field  of  a  Magnet 330,  331 

128,  129.  Generating  Current  by  Revolving  Loop 334 

130.  Two-  and  Three-phase  Current  Waves 335 

131.  Watt-less  Current  (Diagram) 337 

132.  Alternate  Current  (Diagram) 337 

133.  Alternate  Current  Transformation 343 

134.  Transmission  Line  Towers  and  Poles 363 

135.  Transmission  Line  Insulators  and  Pins 365 

136.  137.  Sectional  Armature  and  Revolving  Field  of  a  Three-phase,  Thirty-cycle  Alternator 366 

138.  Continuous-current  Dynamo  coupled  to  the  Turbine  Shaft 366 

139,  140.  General  View  of  Partial  Generator  Installation;   Rotary  Converter 367 

PLANS 

1-6.  Sandusky  River,  Ohio,  Drainage  Basin  and  Topography 77-83 

8,  9.  Direct  Development  in  Alluvial  Location 118,  119 

10,  11.  Short  Diversion  Development 120,  122 

12,  13.  Direct  Development  in  Rock  Gorge 123,  124 

14-16.  Distant  Diversion  Development 125-127 

17.  Divided  Development 128 

18.  Foundation  Design 145 

19.  Upper  Pool,  with  Contour  Lines  showing  Elevations  of  Banks 151 

PROFILES 

1.  Precipitation  and  Run-off,  Green  River,  Ky 35 

2.  Ground-flow  Diagrams 113 

VIEWS 

1.  Breakwater 142 

2.  Timber  Crib 142 

3.  Log  Crib  Coffer 143 

4.  Sheet  Pile  Dike 143 

5.  Steel  Pile  Coffer  (U.  S.  Steel  Pile) 144 

6.  Steel  Pile  Coffer  (Friestedt  Channel  Bar) 145 

7.  Canal  in  Rock,  Excavating  and  Channelling 244 

8.  Canal  in  Rock,  with  Channelled  Sides,  Completed 244 

9.  10.  Canal  in  Earth,  Timber  Lined 245 

11.  Canal  in  Earth,  Timber  Lined,  Completed 246 

12-14.  Canal  Headgates 246,  247 

15.  Power  House  Foundation .' 256 

16.  Power  House  Substructure,  Upstream  View 256 

17.  Power  House  Substructure,  Downstream  Elevation 257 

18.  Power  House  Superstructure,  Upstream  Elevation 257 

18a.  Power  House,  Upstream  View 257 

19.  Power  House  Superstructure.  Downstream  Elevation 257 

20.  Turbine  Bay 257 

21-32.  Submerged  Power  House 272-275 


/  inc.  * 

(f    UNIVERSITY  ) 


HYDRO-ELECTRIC  PRACTICE 


PART  I 

ANALYSIS  OF  A  HYDRO-ELECTRIC  PROJECT 

WHEN  it  is  desired  to  examine  an  undeveloped  water-power  for  the 
purpose  of  producing  electric  current  as  a  commercial  commodity,  experi- 
ence has  taught  that  it  is  best  to  ascertain  first  where  the  product  will 
find  its  market,  and  to  follow  up  a  satisfactory  showing  at  that  end  by 
determining  the  power  capacity  of  the  source,  the  feasibility  of  harness- 
ing the  same,  and  the  cost  of  accomplishing  this.  Observing  this  pro- 
gramme, which  is  really  that  adopted  in  any  commercial  enterprise,  is 
found  to  insure  a  reliable  conclusion. 


CHAPTER   I 

THE    MARKET 

THE  MARKET  of  electric  current  is  to  be  found  in  any  community. 
The  commercial  unit  is  the  product  of  quantity  of  current  and  time  of 
service;  the  measures  are  one  electric  horse-power,  or  one  kilowatt,  and 
the  year  and  hour.  The  horse-power-year  is  the  basis  of  mill  and  factory 
power  contracts,  while  the  kilowatt-hour  is  most  generally  adopted  for 
lighting,  shop,  and  traction  service,  because  of  the  greater  fluctuations 
from  continuous  operations. 

Diagram  I  gives  converted  values  of  the  horse-power  and  kilowatt. 

Electric  current  finds  its  market  for  lighting,  industrial,  and  traction 
service. 

ARTICLE  1. — Lighting  service  consists  of  arc  and  incandescent  lights. 
Arc  lights  are  chiefly  used  for  street,  store,  and  hall  illumination,  and  they 
generally  require  550  watts.  Diagram  I  shows  relative  current  and  power 
for  any  number  of  arcs. 

i 


«  HYDRO-ELECTRIC  PRACTICE 

Arc  service  is  either  of  all-night  or  moonlight  schedule,  and  the  rates 
are  most  frequently  per  lamp  per  year,  ranging  from  $50  up,  the  price 
depending  solely  upon  local  conditions.  Occasionally  arc-lighting  service 
is  per  lamp-hour.  This  branch  of  current  service  is  generally  remunera- 
tive, and  grows  with  the  community  if  the  service  is  at  all  satisfactory. 
Large  stores  and  public  halls,  railroad  depots,  freight  yards,  and  shipping 
docks  are  all  light  customers. 

Incandescent  lights  are  principally  of  16-candle  power,  requiring  55 
watts,  or  one-tenth  of  the  arc-lamp  current.  Diagram  1  serves  to  find 
relative  power.  The  rates  of  incandescent  lighting  are  either  per  lamp 
per  month,  being  denominated  the  "flat  rate,"  or  per  kilowatt-hour, 
mostly  of  a  sliding  scale,  the  price  lowering  as  total  monthly  consumption 
increases;  this  is  termed  the  "meter  rate."  In  cities  incandescent-light 
service  may  be  estimated  at  700  hours  per  year  per  lamp,  representing 
about  38  kilowatt-hours;  in  rural  districts  it  is  somewhat  less.  Meter 
rates  range  from  8  cents  per  kilowatt-hour  up,  depending  entirely  upon 
conditions  of  supply.  The  field  for  this  business  is  in  every  dwelling, 
store,  shop,  mill,  factory,  and  public  institution  and  gathering  place; 
the  number  of  incandescent  lamps  which  can  be  placed  may  generally 
be  taken  as  equal  to  one-half  the  population. 

ARTICLE  2. — Industrial  service  comprises  the  motive  power  used  in 
shops,  mills,  and  factories;  the  current  is  furnished  as  horse-power  per 
year  or  month  to  industries  operating  for  regular  periods  and  with  full 
loads,  and  on  kilowatt-hour  measure  where  periods  and  loads  fluctuate. 
This  service  reaches  every  industry;  for  instance,  the  laundries  and 
printing-shops,  barbers,  hotels,  and  all  places  using  pumps,  fans,  and 
elevators,  saw-mills  and  turning-shops,  grist-  and  flouring-mills,  machine- 
shops,  textile,  woollen,  cotton,  and  knitting-mills,  pulp  and  paper  indus- 
tries, wagon,  buggy,  automobile,  furniture,  piano,  organ-factories,  and, 
in  fact,  every  class  and  kind  of  industry,  none  of  which  are  too  small  to 
use  power  in  some  form  or  other.  The  power  quantity  used  depends 
upon  the  character  and  size  of  the  industry;  a  laundry  may  use  10  horse- 
power, printing-shops  about  5  horse-power  per  press,  wood-working  shops 
5  horse-power  and  metal  shops  10  horse-power  per  machine,  grist-mills 
one-half  horse-power  and  flour-mills  one-third  horse-power  per  barrel 
capacity,  ground  wood-pulp  mills  75  horse-power,  sulphite-pulp  13  horse- 
power, paper-mills  18  horse-power  per  ton  output. 

ARTICLE  3. — There  is  also  a  special  class  of  manufactures  in  which 


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Diagram    1. 

Horse    Power    and 
Kilowatts 

Power    f&r    lighting 
ten    inc.  -  one    arc. 

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10 
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123456789    Kilowatts 

4  HYDRO-ELECTRIC  PRACTICE 

electricity,  in  its  heating  or  decomposing  capacity,  forms  the  most  im- 
portant part  and  cost  of  the  process,  such  as  the  production  of  calcium 
carbide,  carbolite,  carborundum,  and  glass;  the  group  which  requires 
such  intense  heat  as  4000°  to  7000°  F.,  which  can  be  obtained  more 
economically  from  the  electric  current  than  from  any  other  source;  also 
the  .manufacture  of  soda  ash,  bleaching  powders,  and  aluminum,  which 
are  produced  by  electro-chemical  processes.  These  seek  locations  where 
electric  current  can  be  supplied  cheaply,  provided  they  have  satisfactory 
transportation  facilities.  The  proximity  of  the  raw  materials  from  which 
these  products  are  manufactured  is  desirable,  but  secondary  to  the  cur- 
rent supply;  these  raw  materials  are  limestone  free  from  clays  and 
magnesium,  anthracite  or  good  coking  coal,  sand  high  in  silica,  salt,  and 
clay  high  in  aluminum.  The  amount  of  current  required  by  them  is 
large, — 250  horse-power  per  ton  of  carbide  or  carbolite,  450  horse-power 
per  ton  of  carborundum,  and  1400  horse-power  per  ton  of  aluminum. 

ARTICLE  4. — Traction  is  the  third  class  of  current  service,  and 
concerns  street  and  suburban  railroad  systems.  A  street  car  is  generally 
equipped  with  two  25  horse-power,  an  interurban  car  with  four  50  horse- 
power motors;  but  the  full  amount  of  this  power  is  required  only  for 
the  starting  of  a  loaded  car  on  an  up  grade,  while  a  going  car  on  the  level 
requires  but  from  10  to  50  horse-power,  depending  upon  the  speed;  the 
amount  of  power  current  used,  therefore,  fluctuates  greatly  and  con- 
stantly. The  service  period  covers  from  16  to  18  hours.  This  service 
is  supplied  by  a  variety  of  schedules,  from  the  horse-power-year  to  the 
kilowatt-hour,  with  more  or  less  supplemental  conditions  regarding 
maximum  and  minimum  supply;  the  rates  are  from  three-fourths  to 
one  and  one-half  cent  per  kilowatt-hour. 

ARTICLE  5. — The  highest  remunerative  value  of  current  service  is 
found  in  ten-hour  (day  service)  industrial  power  of  the  smaller  units 
but  steady  loads,  together  with  the  arc  and  incandescent  lighting;  such 
a  service  combination  practically  doubles  the  output, — that  is,  each 
horse-power  performs  double  service,  with  some  provision  for  the  lapping 
of  the  two  separate  duties  for  a  short  period  in  the  evening.  It  is  not 
uncommon  that  the  earning  per  horse-power  with  such  a  market  will 
be  between  $50  and  $60  per  year. 

ARTICLE  6.  Analysis  of  the  Current  Market.  —  For  the  purpose  of 
furnishing  data  to  be  considered  in  connection  with  weighing  the  com- 
mercial possibilities  of  a  hydro-electric  project,  something  better  than 


THE    MARKET  5 

general  information  regarding  power  consumption  should  be  secured, 
by  making  a  personal  canvass  and  ascertaining  from  each  power  user, 
if  possible,  what  type  of  power  plant  furnishes  the  service,  its  capacity 
and  general  condition,  fuel  consumption,  and  other  items  of  operating 
cost;  also  as  to  the  use  of  the  power,  its  application  to  the  machinery, 
the  periods  of  operation  and  fluctuations  of  loads.  When  all  this  infor- 
mation is  tabulated  and  a  general  expression  obtained  from  the  power 
users  as  to  their  willingness  to  entertain  the  substitution  of  electric  current 
at  a  certain  rate,  or  under  the  condition  that  the  electric  power  will  be 
supplied  at  a  price  which  represents  a  material  reduction  from  the  cost 
of  the  steam  power,  an  analysis  of  the  existing  power  conditions  and  the 
value  of  the  market  for  the  hydro-electric  project  can  be  made. 

Such  a  canvass  was  taken  in  the  city  of  Fremont,  Ohio,  in  1906, 
which  will  serve  to  illustrate  the  above  and  furnish  all  the  material 
from  which  market  conclusions  must  be  generally  drawn. 

Fremont,  Ohio,  has  a  population  of  12,000.  Real  property  on  33.3 
per  cent,  valuation  aggregates  $2,040,000.00.  Personal  property  on  40 
per  cent,  valuation  aggregates  $1,022,000.00.  Tax  rate  is  32  mills  on  the 
dollar  valuation..  The  banking  capital  (four  banks)  totals  $275,000.00. 
The  deposits  are  $3,350,000.00. 

Three  steam  roads  and  one  interurban  electric  line  enter  the  city, 
and  other  suburban  roads  are  projected;  an  electric  street  railroad  is 
in  operation.  / 

The  present  source  of  power  in  Fremont  is  from  38  private  steam   / 
plants,  ranging  in  units  from  5  to  300  horse-power  capacity,  with  a  total 
of  about  2800  horse-power;    and  from  the  Fremont  Gas  and  Electric 
plant,  dispensing  about  250  horse-power 

The  price  of  steam  coal  is  from  $2.15  to  $3.00  per  ton. 

POWER  USERS  TABULATED. 

Age  of  Steam     Horse-      Operates,          Load         Will  contract 
No.  Concern.  Plant.          power.         Hours.          Factor.         for  Current. 

1.  City  water  works 10  300  18               X 

2.  Light  plant 15  250  . .                X 

3.  Sugar  factory 5  200  24  Sept.-Jan. 

4.  Carbon  factory  (enlarging) 20  200  10               80 

5.  Cutlery  factory  (enlarging) 22  70  10               80             Yes 

70  12  80 

40  20  60 

6.  Street  railway 10  160  18  X 

7.  Knife  and  shear  works 10  150  10  80  Yes 


HYDRO-ELECTRIC  PRACTICE 


Horse- 
power. 


Age  of  Steam 
No.  Concern.  Plant. 

8.  Carriage  forgings 25 

9.  Sash  and  door  mill 30 

10.  Furniture  works 15 

11.  Engine  and  boiler  works 40 

12.  Ladies'  underwear 17 

13.  Malt-extract  plant 25 

14.  Sash  and  door  mill 5 

15.  Agricultural  implements 20 

16.  Flouring  mill,  3  months 20 

9  months 

17.  Flour  mill W.  P. 

18.  Cutlery  works 5 

19.  Grain  elevator 5 

20.  Stove  works 3 

21 .  Stove  works  (building) 

22.  Cutlery  works  (enlarging) 10 

23.  Grain  elevator 18 

24.  Marble  works 15 

25.  Wood-turning  shop 20 

26.  Mitten  and  glove  works 5 

27.  Flour  mill 20 

28.  Feed  shop 15 

29.  Print  shop  (enlarging) 5 

30.  Print  shop 10 

31.  Account  file  works 5 

32.  Organ  works 20 

33.  Cutlery  works 5 

34.  Brewery  (enlarging) 25 

35.  Newspaper 30 

36.  Printing  shop 10 

37.  Laundry 20 

38.  Laundry 10 

"X"  represents  fluctuating 


The  information  found  from  this  inventory  is: 


Operates, 
Hours. 


150 

10 

150 

10 

100 

10 

75 

10 

75 

10 

75 

10 

75 

10 

70 

10 

65 

10 

65 

24 

60 

10 

50 

10 

50 

X 

40 

10 

40 

10 

30 

10 

30 

X 

30 

10 

30 

10 

30 

10 

25 

10 

25 

X 

20 

10 

20 

10 

20 

10 

15 

10 

15 

10 

10 

10 

6 

10 

5 

10 

5 

10 

5 

10 

conditions. 

Load 
Factor. 

75 
80 
80 
75 
75 
75 
80 
60 
100 
100 
100 
75 
X 
75 
75 
75 
X 
80 
75 
75 
100 
X 
80 
80 
80 
75 
80 
100 
75 
75 
80 
80 


Will  contract 
for  Current. 


Yes 

Yes 

Yes 

Yes 
Yes 

Yes 
Yes 

Yes 
Yes 
Yes 
Yes 

Yes 


Yes 
Yes 
Yes 
Yes 


Total  horse-power  now  in  use 

Total  horse-power  in  use  5  years  ago . 
Total  horse-power  in  use  10  years  ago. 


And  this  comparison  of  growth  may  be  extended. 


.2,911  H.P. 
.2,371  H.P. 
.1,701  H.P. 


Total  horse-power  used  for  lighting  service. 
Total  horse-power  used  for  industrial  service. 
Total  horse-power  used  for  traction  service. . 
Industrial  power  of  constant  10-hour  duty.  . 
Industrial  power  of  constant  12-hour  duty. . 
Industrial  power  of  constant  18-hour  duty.  . 
Industrial  power  of  constant  20-hour  duty.  . 
Industrial  power  of  constant  24-hour  duty.  . 
Industrial  power  of  intermittent  duty 


250  H.P. 
.2,501  H.P. 
.  160  H.P. 
.1,656  H.P. 
.  70  H.P. 
.  460  H.P. 
.  40  H.P. 

.     685  H.P. 


THE    MARKET 


Every  power  user  was  solicited  to  express  his  willingness  to  take 
hydro-electric  current,  with  the  result  that  tentative  agreements  for 
power  service  were  made  with  these  concerns  for  power,  service  and  at 
rates  as  follows: 


Power. 

Service, 

Annual  Value  at 

No.                                      Concern. 

H.P. 

Hours. 

Rate.               100  per  cent.  Load. 

5.  Cutlery  factory  

.240 

10 

$35.00  per  H.P. 

$8,400.00 

12 

20 

7.  Knife  factory  

.150 

10 

l^c.  Kw.  h. 

6,860.00 

10.  Furniture  works  

.100 

10 

IJc.  Kw.  h. 

4,575.00 

12.  Ladies'  underwear  

.   75 

10 

2c.  Kw.  h. 

4,575.00 

14.  Sash  and  door  mill  

.   75 

10 

2c.  Kw.  h. 

4,575.00 

15.  Agricultural  implements  

.  70 

10 

2c.  Kw.  h. 

4,270.00 

16.  Flour  mill  

.   65 

10 

2c.  Kw.  h. 

8,177.00 

24 

18.  Cutlery  works  

.   50 

10 

2c.  Kw.  h. 

3,050.00 

20.  Stove  works  

.   40 

10 

3c.  Kw.  h. 

3,660.00 

22.  Cutlery  works  

.   30 

10 

3c.  Kw.  h. 

2,745.00 

23.  Grain  elevator  

.   30 

X 

3c.  Kw.  h. 

2,745.00 

24.  Marble  works  

.   20 

10 

4c.  Kw.  h. 

2,440.00 

25.  Wood-turning  shop  

.   30 

10 

3c.  Kw.  h. 

2,745.00 

28.  Feed  shop  

.   25 

10 

3c.  Kw.  h. 

2,187.00 

33.  Cutlery  works  

.   15 

10 

3c.  Kw.  h. 

1,372.00 

34.  Brewery  

.   30 

10 

3c.  Kw.  h. 

2,745.00 

35.  Newspapers  

.     6 

10 

5c.  Kw.  h. 

915.00 

36.  Printing  shop  

.     5 

10 

6c.  Kw.  h. 

915.00 

To  these  were  added  sundry  prospective  customers  using  fans  and  other 

small  motors,  aggregating  100  H. 

P.  for 

10  hrs.  ( 

^  4c  

12,200.00 

No  agreement  could  then  be  reached  with  the  city  for  its  power 
service,  nor  with  the  electric-light  and  railway  company. 

The  total  horse-power  in  sight  for  immediate  contracts  aggregated 
1056  horse-power  with  a  100  per  cent,  load  factor  revenue  of  $79,156.00, 
of  which  an  estimate  covering  a  horizontal  load  factor  of  70  per  cent, 
and  a  corresponding  revenue  of  $55,000.00  was  accepted  as  being  repre- 
sentative of  the  current  business  which  could  be  secured,  being  a  gross 
income  per  horse-power  of  $45.00. 

The  investment  involved  in  this  project  was $175,000.00 

The  output 2,200  H.P. 

Fixed  charges  (see  Report,  Art.  30) 

Total  charge 30,240.00 

Surplus 23,814.00 

This  example  is  typical  of  a  large  number  of  power  markets  and  of 
the  analysis  which  should  be  secured  of  it. 


CHAPTER  II 

POWER    OPPORTUNITY 

WATER-POWER  is  the  physical  effect  of  the  weight  of  falling  water. 
One  cubic  foot  of  water  weighs  62.5  pounds,  and  when  this  mass  falls 
one  foot  the  resultant  energy  is  62.5  foot-pounds,  when  it  falls  ten  feet 
it  is  625  foot-pounds. 

The  unit  of  power  is  the  energy  which  lifts  550  pounds  one  foot  in 
one  second,  being  termed  one  horse-power,  and  water-power  is  there- 
fore expressed  by  the  product  of  the  weight  of  water  and  height  of  its 
fall  divided  by  550,  the  period  of  time  being  one  second, — i.e., 

H.  P.  =  Q  (flow  per  second)  X  62.5  X  h  (fall)  4-  550. 

The  components  of  the  power  product  are,  consequently,  flow  and  fall. 

The  horse-power  equivalent  of  the  product  of  a  hydro-electric 
development  is  electric  horse-power,  being  so  much  of  the  original  water- 
power  energy  as  remains  available  for  work  in  the  shape  of  electric  current. 

ARTICLE  7. — The  flow  is  the  volume  which  passes  a  given  point 
continuously. 

Precipitation  is  the  prime  source  of  stream  flow ;  it  is  the  only  source, 
excepting  of  rivers  in  the  Arctic  region  which  are  yet  glacier  fed. 

Rain,  dew,  snow,  hail — all  these  are  embraced  under  precipitation. 

When  rain  falls  upon  the  ground,  its' greater  part  sinks  into  the 
soil;  the  other  portion  runs  off  the  surface  into  the  catchment  basin, 
or  remains  for  a  time  on  the  surface  if  it  be  level.  The  quantity  which 
passes  into  the  ground  depends  upon  the  conformation  of  its  surface, 
the  porosity,  depth,  and  degree  of  saturation  of  the  material  comprising 
it;  this  is  the  ground  water',  the  portion  flowing  off  the  surface  is  the 
storm  run-off. 

Ground  water  continues  to  sink  down  and  to  move  laterally  by 
force  of  gravity  as  rapidly  as  the  voids  and  frictional  resistances  of  the 
material  through  which  it  passes  permit,  and  finally  finds  its  way  to  its 
destination,  the  nearest  stream  valley;  but  part  of  the  ground  water  is 
retained  by  the  roots  of  vegetation,  rises  through  them  up  the  stems 
and  tree  trunks,  is  converted  into  cellular  fibre  or  exhaled  as  vapor  from 

8 


POWER   OPPORTUNITY  9 

vegetation,  or  from  the  surface,  into  the  atmosphere,  to  be  collected  and 
again  precipitated. 

Precipitation  falling  on  water  partially  flows  toward  the  destination 
and  part  of  it  is  vaporized. 

All  the  water  which  is  consumed  by  vegetation  and  which  is  vaporized 
is  evaporation;  all  that  portion  which  finds  its  way  into  the  stream  is 
the  run-off. 

As  precipitation  is  the  source,  so  is  ground  water  the  sustenance  of 
stream  flow,  and  the  storage  capacity  of  the  ground  is  the  key  by  which 
the  flow  characteristics  must  be  sought;  in  other  words,  while  precipita- 
tion is  essential  as  the  source  of  flow,  its  quantity  is  not  necessarily  an 
index  of  proportionate  flow;  ground  storage  and  the  constancy  with 
which  it  feeds  the  stream  are  the  criteria  to  be  applied  when  stream 
flow  is  studied. 

It  becomes  first  necessary  to  measure  the  drainage  area  and  examine 
its  topography,  geology,  flora,  and  culture. 

ARTICLE  8. — The  drainage  area  comprises  all  that  country  which 
drains  into  the  system  of  the  stream  above  the  point  under  investigation. 

A  topographical  map  shows  the  water-shed,  height  of  land,  or  divide 
along  which  the  drainage  separates,  passing  down  in  opposite  directions 
into  the  feeders  of  adjacent  streams,  and  its  demarcation  will  give  the 
correct  boundary  of  the  drainage  area.  Topographical  maps  are  not 
always  procurable,  nor  do  such  exist  excepting  for  limited  areas  to  which 
the  operations  of  Federal  or  State  surveys  have  been  extended.  When 
such  a  map  is  not  available,  the  drainage  area  may  be  found  from  State 
or  County  maps  by  marking  its  boundary  as  passing  midway  between 
the  apparent  heads  of  tributaries  or  parallel  watercourses  draining  into 
neighboring  stream  systems.  This  method  will  result  in  a  very  close 
approximation  of  the  correct  drainage  area.  The  unit  measure  to  be 
applied  to  the  marked  area  is  the  square  mile  as  per  scale  of  the  map 
utilized.  Care  must  be  taken  in  this  operation,  especially  when  the  map 
scale,  as  is  frequently  the  case,  is  fractional;  when  enlargement  is  made 
by  pantagraph,  the  ratio  must  be  verified  from  a  standard  unit  and 
multiples  of  it.  State  and  County  maps  of  Northern,  Western,  and  Middle 
States  show  the  section  and  township  lines,  marking  the  areas  of  one  and 
of  thirty-six  square  miles,  respectively.  This  is  not  the  case  in  the  Eastern 
and  Southern  States, — that  is,  in  the  territory  of  the  original  colonies,— 
in  which  geographical  subdivision  boundaries  pay  no  heed  to  meridians 


10  HYDRO-ELECTRIC   PRACTICE 

and  parallels.  The  Rand  &  McNally  State  maps  are  probably  the  best 
for  this  purpose,  when  topographical  plans  cannot  be  had ;  railroad  maps 
are  not  reliable. 

Chart  1  shows  the  demarcation  of  the  drainage  area  of  the  Green 
River,  Ky.,  above  the  United  States  lock  No.  5,  and  Table  1  gives  the 
drainage  areas  of  some  of  the  streams  in  the  United  States  and  Canada 
as  appearing  in  Federal  and  State  survey  records,  and  others  computed 
by  the  author;  from  this  table  a  close  approximation  can  be  made  of 
drainage  areas  for  points  not  therein  quoted,  and  without  actually  pro- 
jecting them,  by  comparison  with  a  greater  or  smaller  one  on  the  same 
stream. 

TABLE  1.— RIVERS'  DRAINAGE  AREAS  AND  LOW  MONTHLY  FLOW,  MEASURED  TO 
DATE,  FROM  FEDERAL  AND  STATE  SURVEY  RECORDS. 

(Drainage  areas  in  square  miles;  flow  in  cubic  second  feet.) 

Drainage     Low 
River.  Tributary  of  Area.      Flow.  Year.  At  State. 

Alabama Mobile 15,400  0.35  '04-'05     Selma Ala. 

Alcovy Ocmulgee 395  0.638  '06        Stewart Ga. 

Allegheny Ohio 1,643  0.196  '06        Redhouse N.  Y. 

Alleghany Ohio 8,688  0.238  '06        Kittanning Pa. 

Alleghany Ohio 11,107  mouth 

Lower  Ammonoosuc Connecticut 388  0.797  '06        mouth Vt. 

Androscoggin 1,500  0.867  '06        Shelburne N.  H. 

Androscoggin 2,090  0.612  '06        Rumford  Falls Me. 

Androscoggin 2,230  0.812  '06        Dixfield Me. 

Androscoggin _. 3,120  Lewiston   Me. 

Androscoggin 3,700  Brunswick Me. 

Animas San  Juan 812  0.3  '05        Durango Colo. 

Antietam Potomac 293  0.5  '04-'05     Sharpsburg Md. 

Apalachee Oconee 440  0.25  '04-'05     Buckhead Ga. 

Apple St.  Croix 427  mouth Wis. 

Appomatox James 745  0.25  '04-'05     Mattoax Va. 

Appomatox James 1,565  mouth Va. 

Arkansas Mississippi 3,060  0.1  '05        Canyon  City Colo. 

Arkansas Mississippi 4,600  0.06  '05        Pueblo Colo. 

Arkansas Mississippi 24,960  0.004  '05        Syracuse Kas. 

Arkansas Mississippi 34,000  0.004  '04-'05     Hutchinson Kas. 

Arkansas Mississippi 188,000  mouth 

Aroostook St.  John 2,230  0.097  '03-'04     Ft.  Fairneld Me. 

Arroyo  Seco 215  0.04  '06        Soledad Cal. 

Ashuelot Connecticut 422  N.  H. 

Asotin  Creek 171  0.17  '06        Asotin Wash. 

Auglaize Maumee 2,541  Tiffin Ohio 

Au  Sable 1,425  0.75  '02-'05     Bamfield Mich. 

Bad 636  mouth Wis. 

Bald  Eagle  Cr Susquehanna 725  mouth N.  Y. 

Bannister Dan 500  mouth Va. 

Batten  Kill Hudson 457  Vt.,  N.  Y. 

Bear 263  0.1  '06        Wheatland Cal. 

Bear 3,940  Soda  Springs Ida. 

Bear 4,500  0.045  '05        Preston Ida. 


POWER   OPPORTUNITY 


11 


HYDRO-ELECTRIC   PRACTICE 


River. 


Tributary  of 


Drainage    Low 
Area.      Flow. 


0.004 


Bear 6,000 

Beaver Ohio 3,030 

Belle  Fourche Cheyenne 4,270 

Big  Blackfoot Missoula 2,465 

Big  Blue Kansas 9,574 

Big  Cottonwood Minnesota 1,000 

Big  Horn Missouri 8,184 

Big  Horn Missouri 20,720 

Big  Muddy Mississippi 2,374 

Big  Sandy Ohio 3,950 

Big  Sioux Missouri 7,880 

Big  Tarkio Missouri 543 

Big  Thompson South  Platte 305 

Big  Thompson South  Platte 862 

Bitterroot Missoula 1,550 

Bitterroot Missoula 3,260 

Blackfoot Missoula 1,016 

Blackfoot Missoula 2,465 

Black White 8,810 

Black White 417 

Blacklick 403 

Black 810 

Black 1,851 

Black Mississippi 2,272 

Blackstone Providence 458 

Black  Warrior Tombigbee 1,020 

Black  Warrior Tombigbee 1,900 

Black  Warrior Tombigbee 4,900 

Black  Warrior Tombigbee 6,500 

Blue Kansas 9,490 

Boardman Kansas 295 

Boise Snake 2,450 

Boise Snake 2,614 

Boise Snake 3,360 

Bois  Brule Menominee 1,013 

Boulder  Creek South  Platte 936 

Boyle Missouri 1,123 

Brazos 30,750 

Brazos 44,000 

Broad Savannah 762 

Broad Savannah 1,500 

Broad Congaree 4,610 

Bruneau Snake 1,800 

Bully  Creek 650 

Cache  Creek Sacramento  ....  500 

Cahaba Alabama 1,040 

Cahaba Alabama 1,950 

East  Canada  Cr Mohawk 256 

East  Canada  Cr Mohawk 283 

West  Canada  Cr Mohawk 364 

West  Canada  Cr Mohawk 

West  Canada  Cr Mohawk 

West  Canada  Cr Mohawk 

Canadian Arkansas 46,000 

Cannon  Ball 3,650 

Cape  Fear 4,493 

Cape  Fear 8,400 


Year. 
'04 


At 


State. 


0.027 
0.165 


'05 
'05 


0.025 
0.07 


'05 
'05 


0.03 
0.17 
0.09 


'05 
'04 
'05 


0.026 
0.44 


'04 
'06 


0.643 


'06 


0.25 


0.1 


'04-'05 
'04-'05 


0.22 


'05 


0.01  '05 

0.04  '04-'05 

0.45  '04-'05 


1.05 


'06 


0.005  '06 

0.16  '06 

0.20  '04-'05 


0.453 
0.821 


'05 
'05 


518 
548 
569 


0.002 


'05 


Collinston Ida. 

mouth Pa. 

Belle  Fourche S.  Dak. 

Bonner Mont. 

mouth Nebr. 

mouth Minn. 

Thermopolis Wyo. 

Fort  Custer Mont. 

mouth Miss. 

mouth Ohio 

mouth Dak. 

mouth Iowa 

Arkins Colo. 

mouth Colo. 

Grantsdale Mont. 

Missoula Mont. 

Presto Ida. 

Bonner Mont. 

mouth Mo. 

Elyria Ohio 

Blacklick Pa. 

Lyons  Falls N.  Y. 

Felts  Mills N.  Y. 

mouth .• Wis. 

Providence R.  I. 

Palos ,. Ala. 

Cordova Ala. 

Tuscaloosa Ala. 

mouth Ala. 

Manhattan Kas. 

Traverse  City Mich. 

Boise  City Ida. 

Highland Ida. 

Caldwell Ida. 

mouth Mich. 

mouth Colo. 

mouth Mo. 

Waco Tex. 

Richmond Tex. 

Carlton Ga. 

mouth Ga. 

Alston S.  C. 

Grandview Ida. 

Vale Oregon 

Lower  Lake Cal. 

Centreville Ala. 

Ala. 

Dolgeville.... N.  Y. 

mouth N.  Y. 

Twin  Rock  Bridge N.  Y. 

Middleville N.  Y. 

Herkimer N.  Y. 

mouth N.  Y. 

N.  Mex. 

Stevenson N.  Dak. 

Fayetteville N.  C. 

.  N.  C. 


POWER   OPPORTUNITY 


13 


River. 


Tributary  of 


Drainage     Low 
Area.       Flow. 


Carrabassett. Kennebec. 

Carson 

Carson 

Carson,  East  Fork 

Carson,  East  Fork 

Carson,  West  Fork 


9,100 
886 


340 
988 
988 
381 
414 
70 
Cashe  Creek  .............................      1,280 

Catawba  .................  Santee  ..........        758 

Catawba  .................  Santee  ..........      1,514 

Catawba  .................  Santee  ..........     2,635 

Catawba  .................  Santee  ..........     2,987 

Catawba  .................  Santee  ..........     5,225 

Catskill  Creek  .......................  ____         263 

Cedar.  .  .  .  ...............  White  ..........     6,317 

Cedar  ...................  White  ..........     7,715 

Cedar  ...................................         170 

Chama  .................................     2,300 

Chariton  .................  Missouri  ........      2,900 

Chattahoochee  ............  Appalachicola  .  .  .      1,170 

Chattahoochee  ............  Appalachicola.  .  .     3,300 

Chattahoochee  ............  Appalachicola.  . 

Cheat  ...................  Monongahela.  .  . 

Cheat  ...................  Monongahela  ----      1,375 

Cheat  ...................  Monongahela  ----      1,559 

Chelan  ..................................        950 

Chemung  ................  Susquehanna.  .  .  .      2,500 

Chenango  ................  Susquehanna.  .  .  .      1,540 

Chewaucan  ..............................         272 

Cheyenne  ................  Missouri  ........     7,350 

Chippewa  ................  Mississippi  ......     6,740 

Chippewa  ................  Mississippi  ......     9,573 

Choccolocco  ..............................        272 

Chowan  ..................  Albemarle  ......     4,870 

Cimarron  ...............................      5,200 

Clackamas  .  .  '.  ............................         800 

Clarion  ..................  Allegheny  .......        865 

Clark  Fork  ..............................     1,550 

Clark  Fork  ..............................     5,960 

Clealum  .................................        205 

Clear  Creek  ..............  South  Platte  ____        345 

Clyde  ....................................        729 

Clyde  ...................................        807 

Clyde  ...................................        869 

Colorado  ................................  138,600 

Colorado  ................................  225,000 

Colorado  ................................   37,000 

Colorado  ................................   40,000 

Columbia  ...............................   81,133 

Conasauga  ..............................         723 

Conecuh  ................................      1,290 

Conemaugh  ..............  Allegheny  .......        711 

Conemaugh  ..............  Allegheny  .......      1,403 

Congaree  .................  Santee  ..........     7,965 

Connecticut  .............................      3,305 

Connecticut  .............................     7,700 

Connecticut  .............................      8,660 

Connecticut  .............................    10,234 


0.602 
0.11 
0.006 
0.18 


Year. 

'05 

'06 

'05 

'04-'05 


At 


State. 


0.34 
0.13 
0.54 
0.79 
0.77 


'05 
'06 

'04-'05 
'04 
'05 


0.068 
0.19 


'05 
'04-'05 


1.26 


'06 


0.70 
0.37 


'05 
'04-'05 


1.00 

0.084 

0.248 

0.12 

0.0008 

0.45 


'06 
'06 
'06 
'06 
'06 
'04-'05 


0.88 


'06 


1.11 


'06 


0.09 
0.18 
1.43 
0.38 


'06 
'06 
'06 
'06 


0.06 
0.025 
0.006 
0.02 


'05 
'04-'05 

'06 
'04-'05 


0.163         '04-'05 


0.485 
0.575 


'06 
'06 


North  Anson Me. 

Empire Nev. 

Empire Nev. 

Gardnerville Nev. 

Rodenbahs Nev. 

Woodfords Cal. 

Yolo Cal. 

Morganton N.  C. 

Catawba S.  C. 

Camden S.  C. 

Rockhill S.  C. 

N.  C.,  S.  C. 

South  Cairo N.  Y. 

Cedar  Rapids Iowa 

Minn.,  Iowa 

Ravensdale Wash. 

Abiquin N.  Mex. 

Iowa,  Mo. 

Norcross Ga. 

West  Point Ga. 

Ga. 

Rowlesburg W.  Va. 

Uneva W.  Va. 

W.  Va. 

Chelan Wash. 

Chemung N.  Y. 

Binghamton N.  Y. 

Paisley Oregon 

Edgemont S.  Dak. 

Eau  Claire Wis. 

Wis.,  Mich. 

Jenifer Ala. 

Va.,  N.  C. 

Arkalon Kas. 

Barton Oregon 

Clarion Pa. 

Grantsdale Mont. 

Missoula Mont. 

Roslyn Wash. 

Forkscreek Colo. 

Lyons N.  Y. 

Clyde. N.  Y. 

mouth N.  Y. 

Hardyville Ariz. 

Yuma Ariz. 

Austin Tex. 

Columbus Tex. 

Wash. 

N.  Y. 

Beck Ala. 

Johnstown Pa. 

Saltsburg Pa. 

S.  C. 

Orford N.  H. 

Sunderland Mass. 

Holyoke Mass. 

Hartford Conn. 


14  HYDRO-ELECTRIC   PRACTICE 

Drainage  Low 

River.                               Tributary  of  Area.  Flow.              Year.                            At                             State, 

Connecticut 10,924     N.  H.,  Vt.,  Mass.,  Conn. 

Contoocook Merrimac 410     0.400            '06        West  Hopkinton N.  H. 

Contoocook Merrimac 766     N.  H. 

Coosa Alabama 4,006     0.30           '04-'05     Rome Ga. 

Coosa Alabama 7,053     Lock  No.  4 Ala. 

Coosa Alabama 7,065     0.970            '06        Riverside Ala. 

Coosa Alabama 7,648     Lock  No.  5 Ala. 

Coosawattee  Coosa 531     2.02              '06        Carters Ga. 

Croton 339     0.521         '01-'04     old  Croton  Dam N.  Y. 

Croton 360     new  Croton  Dam N.  Y. 

Crow  Creek Mississippi 3,085     Colo, 

Crow  Wing Mississippi 3,560 

Cumberland Ohio 13,987     .....          Lock  "A" Tenn. 

Cuyahoga 698     0.57              '05        Independence Ohio 

Dakota Missouri 22,000     Dak. 

Dan Roanoke 2,750     0.39           '04-'05     South  Boston Va. 

Dan Roanoke 3,700     Va.,  N.  C. 

Dan Roanoke 3,798     Clarksville Va. 

Dead Kennebec 870     0.198         '02-'05     The  Forks Me. 

Dead Kennebec 1,000     Me. 

Deep Cape  Fear 1,110     Cumnock N.  C. 

Deep Cape  Fear 1,350     N.  C. 

Deep Cape  Fear 1 ,400     Moncure N.  C. 

Deerfield Connecticut 646     0.611             '06        Deerneld Vt.,  Mass. 

Delaware,  East  Branch 920     0.407            '06        Hancock N.  Y. 

Delaware 1,604     junction  E.  and  W.  branches 

Delaware 2,580     Pa.  State  line 

Delaware 3,252     Port  Jervis N.  Y. 

Delaware 3,600     mouth  of  Neversink 

Delaware 4,176     Delaware  Gap N.  J. 

Delaware 6,855     Lambertville N.  J. 

Delaware 10,100     N.  Y.,  Pa.,  N.  J. 

Delaware 11,895     Wilmington Del. 

Delaware,  West  branch 519     Deposit N.  Y, 

Delaware,  West  branch 685     mouth 

Deschutes Columbia 9,900     Moro Oregon 

Deschutes,  East  Fork Columbia 196     0.19               '06        Odell Oregon 

Deschutes,  West  Fork 360     2.40               '06        Lava Oregon 

Deschutes 880     0.12              '06        Lava Oregon 

Deschutes 1,240     1.06               '06        West's  Ranch Oregon 

Deschutes 9,180     0.59               '06        Biggs Oregon 

Des  Moines Mississippi 6,462     0.13           '04-'05     Des  Moines Iowa 

Des  Moines Mississippi 14,290     0.173            '06        Keosauqua Iowa 

Des  Plaines Illinois 633     Riverside ,  .111. 

Eau  Claire Chippewa 899     Wis. 

Elk Mississippi 1,700     0.50               '06        Elkmond Ala. 

Elkhorn Platte 2,474     Norfolk Nebr. 

Elkhorn Platte 5,980      Arlington Nebr. 

Elkhorn Platte 6,732     Nebr. 

Enoree Broad 730     N.  and  S.  C. 

Escanaba 800     0.514             '06        Escanaba Mich. 

Etowah Coosa 930     0.46              '04         Canton Ga. 

Etowah Coosa 1,854     0.23              '04        Rome Ga. 

Fall 390     1.10              '06        Fremont Ida. 

Fall Snake 390     0.96              '05        Fremont Ida. 

Fall Snake 594     5  miles  above  mouth Ida. 

Fall..                                 ..Snake 913     mouth Ida. 


POWER   OPPORTUNITY  15 

Drainage  Low 

River.                                Tributary  of  Area.  Flow.              Year.  At                             State. 

Feather 506  1.20              '05        Prattville Cal. 

Feather 3,640  0.36              '05        Oroville Cal. 

Farmington Connecticut 584  Mass,  and  Conn. 

Flambeau 2,120  0.55              '06        Ladysmith Wis. 

Flint 2,700  0.42               '05        Montezuma Ga. 

Flint Chattahoochee..  988  0.20           '04-'05     Woodbury Ga. 

Flint Chattahoochee  . .  5,000  0.40           '04-'05     Albany Ga. 

Flint Chattahoochee..  8,420  , Ga. 

Floyd Missouri 1,014  Iowa 

Fox Wisconsin 2,697  Wis. 

French  Broad 325  0.79               '04        Horseshoe N.C. 

French  Broad Tennessee 987  0.88              '05        Asheville N.C. 

French  Broad Tennessee 1,737  0.45           '04-'05     Oldtown Tenn. 

French  Broad Tennessee 5,133  mouth Tenn. 

Gallatin 1,620  0.14              '05        Logan Mont. 

Gasconade Missouri 2,725  0.25           '04-'05     Arlington Mo. 

Gasconade Missouri 3,667  Mo. 

Genesee 143  below  Cryder  Cr N.  Y. 

Genesee 211  Chenunda  Cr. 

Genesee 323  Vandemarsh  Cr. 

Genesee 346  Knights  Cr. 

Genesee 405  Phillips  Cr. 

Genesee 466  Van  Campens  Cr. 

Genesee 563  Angelica  Cr. 

Genesee 585  White  Cr. 

Genesee 627  Upper  Black  Cr. 

Genesee 649  Crawford  Cr. 

Genesee • 714  Caneadea  Cr. 

Genesee 786  Cold  Cr. 

Genesee 822  Rush  Cr. 

Genesee 942  Wiscoy  Cr. 

Genesee 994  Wolf  Cr. 

Genesee 1,060  Silver  Lake  Cr. 

Genesee 1,070  0.25           '03-'05     Mount  Morris N.  Y. 

Genesee 1,142  Coshaqua  Cr. 

Genesee 1,407  Canaseraga  Cr. 

Genesee 1 ,464  Beards  Cr. 

Genesee 1,644  Conesus  Cr. 

Genesee 1,939  Honeoye  Cr. 

Genesee 2,145  Aliens  Cr. 

Genesee 2,365  0.222             '06        Rochester N.  Y. 

Genesee 2,380  Black  Cr N.  Y. 

Genesee 2,496  Pa.  and  N.  Y. 

Gila Colorado 2,450  0.066            '05        Cliff N.  Mex. 

Gila Colorado 13,460  0.00062        '04        San  Carlos Ariz. 

Gila Colorado 17,834  Buttes Ariz. 

Gila Colorado 71,050  0.00075        '05        Dome Ariz. 

Grand 1,230  0.28              '05        North  Lansing Mich. 

Grand 4,900  0.57              '05        Grand  Rapids Mich. 

Grand Colorado 2,380  0.20               '06        Kremmling Colo. 

Grand 4,520  0.14               '06        Glenwood  Springs Colo. 

Grand 2,380  0.13              '05        Kremmling Colo. 

Grand 4,523  0.13              '04        Glenwood  Springs Colo. 

Grand 8,546  0.21               '05        Palisades Colo. 

Grand Missouri 7,932  Iowa  and  Mo. 

Grande  Ronde 1,350  0.04               '06        Elgin Oregon 

Great  Kanawha . .  .  .  Ohio 


16 


HYDRO-ELECTRIC   PRACTICE 


River. 


Tributary  of 


I  > ram. -i in-       Low 

Area.        Flow. 


Year. 


At 


State. 


Great  Miami Ohio 

Great  Pee  Dee 

Great  Pee  Dee 

Great  Pee  Dee 

Green Colorado 

Green Colorado 

Green Colorado 

Green Ohio 

Greenbrier 

Greenbrier 

Guadalupe 

Gunnison Grand 

Gunnison Grand 

Gunnison Grand 

Gunnison Grand 

Haw Cape  Fear 

Heart 

Hiwasscc 

Hiwassee 

Hiwassee 

HiwuKsee 

Holston 

Holston 

Holston,  South  Fork 

Hood 

Hoosic Hudson 

Hoosic Hudson 

Housatonie 

Housatonic 

Hudson. 

Hudson 

Hudson 

Hudson 

Hudson 

Humboldt 

Humboldt 

Humboldt 

Humboldt,  North  Fork 

Humboldt,  South  Fork 

Huron 

Illinois Mississippi 

Illinois Mississippi 

Illinois Mississippi 

Indian  Creek 

Iowa Mississippi 

Iowa Mississippi 

James 

James 

James 

James 

Jefferson 

Jefferson 

John  Day 

Juniata W.  Susquehanna 

Juniata W.  Susquehanna 

Kalamazoo 

Kalamazoo 


5,400 
498 

3,399 
17,000 

7,450 
26,620 
38,200 


0.76 
0.45 


0.075 
0.026 
0.042 


Ohio 

'04  North  Wilkesboro N.  C. 

'04-'05     Salisbury N.  C. 

, N.  and  S.  C. 

'05  Greenriver  Wyo. 

'04  Jensen Utah 

'05  Greenriver  .  ..Utah 


1,575 

1,344 

5,100 

2,298 

3,844 

5,233 

7,868 

1,675 

1,250 

410 

1,180 

2,297 

2,698 

3,060 

3,790 

828 

370 

579 

710 

1,020 

1,933 

1,092 

2,800 

4,500 

8,000 

13,368 

5,014 

10,780 

13,800 

1,020 

1,150 

775 

6,480 

13,250 

29,013 

740 

3,317 

12,519 

2,058 

3,027 

6,232 

9,700 

8,984 

9,400 

7,800 

3,223 

3,476 

847 

1,471 


Va. 

0.15  '04-'05     Alderson W.  Va. 

0.102  '06        Cuero Tex. 

lola Colo. 

0.12  '05  Cimarron Colo. 

0.09  '04-'05  Cory Colo. 

0.11  '04-'05  Whitewater Colo. 

N.  C. 

0.0012  '04-'05  Richardton N.  Dak. 

0.59  '04-'05  Murphy N.  C. 

0.54  '04-'05  Reliance Tenn. 

Charleston Term. 

mouth Tenn. 

0.32  '05  Austins  Mill Tenn. 

mouth Tenn. 

0.27  '04-'05  Bluff  City Tenn. 

1.92  '06  Winans Oregon 

0.370  '06  Buskirk N.  Y. 

Mass.,  Vt.,  and  N.  Y. 

0.484  '05        Gaylordsvillc Conn. 

Mass,  and  Conn. 

Hadley N.  Y. 

0.794  '05  Fort  Edward N.  Y. 

0.583  '04-'05  Mechanicsville N.  Y. 

Troy N.  Y. 

N.  Y. 

0.0068  '05  Palisade Nev. 

0.000025  '05  Golconda Nev. 

0.00014  '05  Oreana Nev. 

0.00051  '05  Elburz Nev. 

0.00  '05  Elko Nev. 

0.110  '06  Geddes Mich. 

1.08  '04  Minooka 111. 

0.50  '06  Peoria 111. 

0.072  '06  Crescent  Mills Cal. 

0.11  '04-'05  Iowa  City Iowa 

Iowa 

0.20  '04-'05  Buchanan Va. 

Balcony  Falls Va. 

0.25  '04-'05  Cartersville Va. 

Va. 

0.07  '04-'05  Sappington Mont. 

Three  Forks Mont. 

0.04  '06  McDonald Oregon 

0.40  '04-'05     Newport Pa. 

below  Battle  Creek ....  Mich. 

0.405  '06        Allegan Mich. 


POWER   OPPORTUNITY 


17 


River. 


Tributary  of 


Drainage 
Area. 


Low 
Flow. 


Year. 


At 


State. 


Kalamazoo 2,064 

Kankakee Illinois 5,300 

Kansas Missouri 58,550 

Kansas Missouri 59,750 

Kaskaskia Mississippi 5,876 

Kaweah 520 

Kennebec .- 1,250 

Kermebec 1 ,670 

Kenntebec 2,570 

Kennebec 2,880 

Kennebec 2,900 

Kennebec 3,330 

Kennebec 4,030 

Kennebec 4,380 

Kennebec 4,410 

Kennebec 5,470 

Kennebec 5,770 

Kennebec 6,400 

Kentucky Ohio 

Kentucky Ohio 7,870 

Kern 2,345 

Kings 1,742 

Kings 1,775 

La  Mine Missouri 2,700 

Laramie North  Platte 3,179 

Laramie North  Platte 4,076 

Lehigh Delaware 1,330 

Licking Ohio 696 

Licking Ohio 3,870 

Little  Bighorn 1,276 


0.07 


'04-'05 


0.23 

0.403 

0.437 


0.403 


'05 


0.089 
0.108 


'05 
'05 


3,461 

6,000 

17,630 

2,290 

600 


Little  Blue Big  Blue. 

Little  Colorado Colorado. 

Little  Colorado Colorado. 

Little  Kanawha Ohio. .  . . 

Little  Missouri 

Little  Missouri 1,900 

Little  Missouri 5,785 

Little  Muddy 800 

Little  Nemaha Missouri 990 

Little  Sioux Missouri 4,223 

Little  Tennessee 682 

Little  Tennessee 2,470 

Little  Wood Snake 1,270 

Locust  Fork  of  Black  Warrior 1,020 

Logan Bear 218 

Loup Platte 13,540 

Loup Platte 15,553 

Luis  Rey '. 318 

North  Loup 4,024 

Machias,  East  and  West 465 

Machias,  East  and  West 800 

Mackinaw Illinois 1,182 

Mad 290 

Madison 2,085 

Madison. .  2,420 


0.143 
0.06 

0.0048 
0.0044 

0.0017 
0.004 
0.0014 
0.0085 


'04 
'05 

'05 
'05 

'05 
'06 
'05 
'05 


mouth Mich. 

111.  andlnd. 

Lecompton Kas. 

mouth 

Three  Rivers Cal. 

Moosehead  Lake Me. 

The  Forks Me. 

below  Dead  River Me. 

North  Anson Me. 

Carritunk  Falls Me. 

Madison Me. 

Norridgewock Me. 

Somerset  Mills Me. 

above  Sebasticook  River.  .Me. 

Waterville Me. 

Augusta Me. 

mouth Me. 

Little  Hickman Ky. 

mouth Ky. 

Bakersfield Cal. 

Sanger Cal. 

Red  Mountain Cal. 

mouth Mo. 

Uva Wyo. 

Ft.  Laramie Wyo. 

Pa. 

Pleasant  Valley Ohio 

Ohio 

Crow  Agency Mont. 

Woodruff Ariz. 

Holbrook Ariz. 

Alzada Mont. 

Camp  Crook S.  Dak. 

Medora N.  Dak. 

Williston..  ..N.  Dak. 


0.66 
0.73 


'04-'05 
'05 


0.22 
0.44 
0.193 


'04-'05 
'06 
'06 


0.01 
0.465 


'06 
'04 


0.445 
0.53 


'05 
'05 


Mahoning 

Malade Snake. 

2 


958 
2,190 


0.174 


'06 


Minn. 

Judson N.  C. 

McGhee Tenn. 

Toponis Ida. 

Palos Ala. 

Logan Utah 

Columbus Nebr. 

Nebr. 

Pala Cal. 

St.  Paul Nebr. 

Whitneyville Me. 

mouth Me. 

111. 

Springfield Ohio 

Norris Mont. 

Threeforks Mont. 

Youngstown Ohio 

Toponis Ida. 


18  HYDRO-ELECTRIC   PRACTICE 

Drainaare  Low 

River.                                Tributary  of  Area.  Flow.  Year.                            At                             State, 

Malade Snake 3,550  Bliss Ida. 

Malheur 4,860  0.01               '06        Vale Oregon 

Maple 459  Maple  Rapids Mich. 

Maple 919  mouth Mich. 

Marias 2,610  0.09           '04-'05     Shelby Mont. 

Mattawamkeag Penobscot 1,510  0.123            '05        Mattawamkeag Me. 

Mattawamkeag Penobscot 1,533  Me. 

Maumee 2.190  0.13              '05        Sherwood Ohio 

McCloud 608  2.27              '06        Gregory Cal. 

McKenzie 960  2.30              '06        Springfield Oregon 

Medicine Arkansas 1,300  Kiowa Kas. 

Meherrin Chowan 1,675  Va.  and  N.  C. 

Menominee 2,415  0.77           '02-'05     Iron  Mountain Mich. 

Menominee 4,113  Mich,  and  Wis. 

Meramee 340  0.44               '04        Meramee Mo. 

Meramec Mississippi 3,497  0.27           '04-'05     Eureka Mo. 

Meramee Mississippi 3,914  Mo. 

Merced 1,090  0.057            '05        Merced  Falls Cal. 

Merrimac 1,460  0.774            '06        Franklin  Junction N.  H. 

Merrimac 4,553  0.390            '06        Lawrence Mass. 

Merrimac 4,916  N.  H.  and  Mass. 

Methow  1,710  0.25              '06        Pateros Wash. 

Miami Ohio 2,450  0.140             '06        Dayton Ohio 

Michigamme Menominee 756  Mich. 

Middle  Loup 6,849  St.  Paul Nebr. 

Milk Missouri 7,300  0.0001           '06        Havre Mont. 

Milk Missouri 14,040  0.00036        '05        Malta Mont. 

Milk,  North  Fork 1,422  0.13              '06        Chinook Mont. 

Minnesota Mississippi 13,400  0.099            '05        Mankato Minn. 

Minnesota Mississippi 16,000  Minn. 

Mississippi 12,400  0.211            '05        Sauk  Rapids Minn. 

Mississippi 36,085  St.  Paul Minn. 

Missoula 5,960  0.14              '05        Missoula Mont. 

Missouri Mississippi 14,500  Townsend Mont. 

Missouri Mississippi 15,036  . 4. . .  .     Canyon  Ferry Mont. 

Missouri Mississippi 17,615  Craig Mont. 

Missouri Mississippi 18,295  0.11              '05        Cascade Mont. 

Missouri Mississippi 492,000  0.05  '05        Kansas  City Mo. 

Missouri Mississippi 527,155  Mont. 

Mohawk Hudson 1,306  0.755         '03-'05     Little  Falls N.  Y. 

Mohawk Hudson 3,440  0.331  '06        Dunsbach  Ferry  Bridge,  N.  Y. 

Mohawk Hudson 3,493  N.  Y. 

Mokelumme 642  0.30              '06        Clements Cal. 

Molalla 220  0.35               '06        Molalla Oregon 

Monongahela Ohio 2,324  Fairmont W.  Va. 

Monongahela Ohio 2,749  Morgantown W.  Va. 

Monongahela Ohio 4,574  Greensboro Pa. 

Monongahela Ohio 5,427  Lock  No.  4 Pa. 

Monongahela Ohio 7,625  W.  Va. 

Montreal Wis. 

Moose Black 349  0.624        '00-'05     Moose  River tN.  Y. 

Moose Kennebec 680  0.174        '02-'05     Rockwood Me. 

Mouse 8,400  0.0019          '06        Minot N.  Dak. 

Muskegon 1,764  above  Big  Rapids Mich. 

Muskegon 2,352  0.389            '06        Newaygo Mich. 

Muskegon 2,663  mouth Mich. 

Muskingum Ohio 5,828  0.329            '06        Janesville Ohio 


POWER  OPPORTUNITY  19 

Drainage     Low 

River.                              Tributary  of  Area.  Flow.             Year.                           At                           State. 

Muskingum Ohio 7,740     Ohio 

Naches 636  0.42               '06        Nile Wash. 

Naches 1,120  0.06               '06        North  Yakima Wash. 

Nashua Merrimac 773     Nashua Mass. 

Nashua,  South  Branch 119  0.543         '97-'05     Clinton Mass. 

Neches 8,200  0.03           '04-'05     Evadale Tex. 

Nemaha Missouri 1 ,924     Kas.  and  Nebr. 

Neosho 3,670     lola Kas. 

Neosho 12,746     Kas.  and  I.  T. 

Neuse 5,300     N.  C. 

New 1,100     Oldtown Va. 

New 2,725  0.44           '04-'05     Radford Va. 

New 4,523     ab.  Greenbrier  River.  .W.  Va. 

New 5,600  Hinton W.  Va. 

New 6,200  0.173            '04        Fayette W.  Va. 

Niobrara Missouri 6,070  0.13              '05        Valentine Nebr. 

Niobrara Missouri 6,300  0.104            '06        Ft.  Niobrara Nebr. 

Niobrara Missouri 13,200 

Nishnabatona Missouri 3,100  Iowa 

Nodaway Missouri 1,886  Iowa 

Nolichucky 640  ab.  Tenn.  State  line 

Nolichucky 817  Chucky  Valley Tenn. 

Nolichucky 1,099  0.44           '04-'05     Greenville Tenn. 

Nottaway Blackwater 1,650  Va. 

Ocmulgee Oconee 1,500  0.22           '04-'05     Jackson Ga. 

Ocmulgee Oconee 2,425  0.17           '04-'05     Macon Ga. 

Ocmulgee Oconee 6,000  Ga. 

Oconee Altamaha 1,100  0.33              '05        Greensboro Ga. 

Oconee Altamaha 1,346  Carey Ga. 

Oconee Altamaha 4,182  0.19           '04-'05     Dublin '.  Ga. 

Oconee Altamaha 5,400  mouth Ga. 

Oconto 1,017  mouth Wis. 

Ogeechee 4,720  Ga. 

Ohio Mississippi 23,820  0.358            '06        Wheeling W.  Va. 

Ohio Mississippi 214,000 

Ohoopee 1,280  0.06              '05        Reidsville Ga. 

Okoee 374  2.28               '06        McCays Tenn. 

Oneida Oswego 1,313  0.563            '05        Euclid N.  Y. 

Oneida Oswego 1,421  N.  Y. 

Oostenaula Coosa 1,614  0.51               '06        Resaca Ga. 

Oostenaula Coosa 2,190  Rome Ga. 

Osage Missouri 15,300  Mo.  and  Kas. 

Oswegatchie ,    . . , 1,580  0  50              '05        Ogdensburg N.  Y. 

Oswego 4,916  Fulton N.  Y. 

Oswego 4,990  0.797         '04-'05     Battle  Island N.  Y! 

Oswego 5,002  mouth N.  Y. 

Otter  Creek Lake  Champlain.  615  0.68              '06        Middlebury Vt. 

Ottertail , 1,310  0  40              '06        Fergus  Falls .  .  .Minn! 

Ouachita Red  River 19,000  Ark! 

Owyhee 9,875  0.0006          '05        Owyhee Oregon 

Palouse 2,210  0.007            '06        Hooper Wash. 

Palouse 2,460  mouth Wash! 

Pascagoula 8,350  Mo. 

Passaic 360  Two  Bridges 

Passaic 960  N  J 

Patapsco 251  0.46              '04        Woodstock ! .  . !  !  Md! 

Patapsco 350  mouth Md! 


20  HYDRO-ELECTRIC   PRACTICE 

Drainage  Low 

River.                              Tributary  of  Area.  Flow.             Year.                           At                           State. 

Paw  Paw St.  Joseph 429     Mich. 

Payette 2,240    0.383  '06        Horseshoe  Bend Ida. 

Pea 1,180    0.15  '04        Pera Ala. 

Pearl 3,120     0.17  '05        Jackson Miss. 

Pearl 8,670     Miss. 

Pembina 2,940     0.038  '06        Neche N.  Dak. 

Pemigewasset Merrimac 615     0.276         '86-'04     Plymouth H.  H. 

Penobscot 1,880     0.225  '05        Millinocket Me. 

Penobscot 3,160      below  mouth  East  branch 

Penobscot 6,630     0.387  '05        West  Enfield Me. 

Penobscot 7,240     Oldtown Me. 

Penobscot 7,910     Bangor Me. 

Penobscot 8,500     Me. 

Penobscot,  East  Branch 1,130     0.196  '05        Grindstone Me. 

Pepacton Delaware 1,919     N.  Y. 

Peshtigo 1,123     mouth Wis. 

Piscataquis Penobscot 280     0.283  '05        Foxcroft Me. 

Piscataquis Penobscot 380     Dover Me. 

Piscataquis Penobscot 750     Sibec  Lake 

Piscataquis Penobscot 1 ,500     mouth 

Pit Sacramento 1,500    0.004  '05        Canby Cal. 

Pit Sacramento 2,948     0.004  '05        Bieber Cal. 

Platte Missouri 2,487     Iowa  and  Mo. 

Platte Missouri 53,300     0.005  '04        Lexington Nebr. 

Platte Missouri 56,867     0.01  J04-'05     Columbus Nebr. 

Platte Missouri 90,000     Nebr. 

North  Platte 7,668     Sweetwater 

North  Platte 14,255     Douglas 

North  Platte 14,828     Orin  Junction 

North  Platte 16,240     0.028  '05        Guernsey Wyo. 

North  Platte 16,416     Fort  Laramie 

North  Platte 20,492     below  Laramie  River 

North  Platte '. 23,190     0.006  '04        Bridgeport Nebr. 

North  Platte 24,340     Gering Nebr. 

North  Platte 24,400     0.018  '05        Mitchell Nebr. 

North  Platte 24,830     Camp  Clarke 

North  Platte 28,520     0.015  '05        North  Platte Nebr. 

North  Platte 36,000     Colo.,  Wyo.  and  Nebr. 

South  Platte Platte... 1,677     Lake  Cheesman Colo. 

South  Platte Platte 2,612     0.04  '04-'05     South  Platte Colo. 

South  Platte Platte 3,840     0.021  '06        Denver Colo. 

South  Platte Platte 9,470     0.015  '06        Kersey Colo. 

South  Platte Platte 20,600     0.001  '06        Julesburg Colo. 

South  Platte Platte 23,294     North  Platte Nebr. 

South  Platte Platte 24;000     Colo,  and  Nebr. 

Potomac 1,487     W.  Va. 

Potomac 2,882     N.  &  S.  branches 

Potomac 3,388     Great  Cacapaw 

Potomac 4,059     bel.  Great  Cacapaw 

Potomac 4,099     Hancock W.  Va. 

Potomac 5,556     Williamsport Md. 

Potomac 6,354     Harpers  Ferry W.  Va. 

Potomac 9,397     below  Harpers  Ferry, 

incl.  Shenandoah 

Potomac 9,654     0.13  '02-'05     Point  of  Rocks Md. 

Potomac 11,100     Edwards  Ferry 

Potomac 11,427     Great  Falls 


POWER   OPPORTUNITY  21 

Drainage  Low 

River.                               Tributary  of  Area.  Flow.              Year.                            At                             State. 

Potomac 11,545     Chain  Bridge D.  C. 

Potomac 14,500 

Potomac,  North  Branch 293     Bloomington Md. 

Potomac,  North  Branch 406     0.065         '04-'05     Piedmont \V .  Va. 

Potomac,  North  Branch 891      Cumberland Md. 

Potomac,  North  Branch 1,365     junction,  South  Br. 

Potomac,  South  Fork 318      junction,  North  Fork 

Potomac,  South  Fork 640     below  Seneca  Creek 

Potomac,  South  Fork 1,198     Moorefield 

Potomac,  South  Fork 1,407     Romney W.  Va. 

Potomac,  South  Fork 1.443     0.305            '06        Springfield W.  Va. 

Potomac,  South  Fork 1 ,475     0.064         '03-'05     Springfield W.  Va. 

Potomac,  South  Fork 1,487 

Potomac,  South  Fork 1,580 

Powder 275     0.04               '06        Salisbury Oregon 

Presumpscot 700     1.11               '06        Me. 

Quinnebaug Shetucket 725     Conn,  and  Mass. 

Raccoon Des  Moines 3,329     Iowa 

Rapid  Creek 410     0.17               '06        Rapid '....S.  Dak. 

Rappahannock 2,700     Va. 

Raquette 1,169     0.518         '04-'05     Massena  Springs N.  Y. 

Raritan 490     0.422             '06         Finderne N.  J. 

Raritan 800     0.551          '03-'05     Bound  Brook N.  J. 

Raritan 1,000     mouth N.  J. 

Red  Cedar 1,840     0.219            '05        Janesville Iowa 

Red Mississippi 40,200     0.075            '06        Arthur  City Texas 

Red Mississippi 92,700     Tex.  and  La. 

Red  River  of  the  North 6,000     0.08              '05        Fargo N.  Dak. 

Red  River  of  the  North 25,800     0.067            '04        Grand  Forks N.  Dak. 

Red  Lake Red 5,525     0.151             '06        Crookston Minn. 

Red  Lake Red 6,518     Minn. 

Red  Water 1,015     0.14           '04-'05     Belle  Fourche S.  Dak. 

Republican Kansas 23,270     0.011             '05        Bostwick Nebr. 

Republican Kansas 24,600     Nebr.  and  Kas. 

Republican Kansas 25,840     0.015         '04-'05     Junction Kas. 

Republican,  South  Fork 5,910     0.001             '06        Benkelman Nebr. 

Republican,  North  Fork 1,390     Haigler 

Richelieu 7,750     0.849            '06         Fort  Montgomery N.  Y. 

Rio  Grande 1,400     0.209            '05        Del  Norte. . . . Colo. 

Rio  Grande 7,695     0.0025          '04        Lobatos Cal.. 

Rio  Grande 14,050     0.025            '05        San  Ildefonso N.  Mex.. 

Roanoke 388     0.255            '06        Roanoke Va. 

Roanoke 3,076     0.35           '04-'05     Randolph Va. 

Roanoke 7,344     Clarksville 

Roanoke 8,717     Neal 

Roanoke 9,200     Va.  and  N.  C. 

Rock Mississippi 6,150     0.104            '06        Rockton 111. 

Rock Mississippi 10,973     111. 

Rock Big  Sioux 1,660     Minn. 

Rocky Savannah 241      S.  C. 

Rogue 2,020     0.65               '06        Tolo Oregon 

Rum Mississippi 1 ,420     0.43               '06        Anoka Minn. 

Sabine 2,900  0.067            '05        Longview 

Sabine 10,400     mouth Tex. 

Saco 385     0.408            '06        Center  Conway N.  H. 

Saco 856     Great  Falls 

Saco 1,366     Highland  Rips 


22  HYDRO-ELECTRIC   PRACTICE 

Drainage  Low 

River.                               Tributary  of  Area.  Flow.              Year.                            At                             State. 

Saco 1,578     Bonny  Eagle  Falls 

Saco 1,750     Me.  and  N.  H. 

Sacondaga Hudson 1,028     N.Y. 

Sacramento 655     Oregon 

Sacramento 9,134     Jellies  Ferry Cal. 

Sacramento 9,295     0.555            '05        Red  Bluff Cal. 

Saint  Croix 500     Little  Falls Me. 

Saint  Croix 1,390     0.806            '04        Spragues  Falls Me. 

Saint  Croix 1,530     0.810            '06        Calais Me. 

Saint  Croix 1,620     mouth Me, 

Saint  Croix Mississippi 7,576     Minn,  and  Wis. 

Saint  Francis Mississippi 8,000      Mo.  and  Ark. 

Saint  John 26,000     0.203            '06        Me.  and  Canada 

Saint  Joseph 863     above  Three  Rivers ....  Mich. 

Saint  Joseph • 1,417     below  Three  Rivers. .  . .  Mich. 

Saint  Joseph 3,616     above  Niles Mich. 

Saint  Joseph 3,898     below  mouth  of  Dowagee 

Saint  Joseph 3,935     0.373            '06        Buchanan Mich. 

Saint  Joseph 4,157     above  Paw  Paw Mich. 

Saint  Joseph 4,586     below  Paw  Paw Mich. 

Saint  Louis 3,272     above  Cloquette Wis. 

Saint  Marys 763     0.059            '06        Fort  Wayne Ind. 

Salinas 4,084     Salinas Cal. 

Saline Smoky  Hill 2,730     Beverley 

Saline Smoky  Hill 3,463     Kas. 

Salmon 259     0.40               '06        Pulaski N.Y. 

Salt Gila 2,880     above  Verde  River 

Salt Gila 5,756     0.036         '04-'05     Roosevelt Ariz. 

Salt Gila 6,260     0.045         '04- '05     McDowell Ariz. 

Salt Gila 12,260     Arizona  Dam Ariz. 

Saluda Broad 1,056     0.51           '04-'05     Waterloo S.  C. 

Saluda Broad 2,350     mouth S.  C. 

Sandy Kennebec 340      Farmington ,  Me. 

Sandy Kennebec 650     0.137         '04-'05     Madison Me. 

San  Diego 208     0.0005          '06         Lakeside Cal. 

San  Francisco 1,800     0.021             '05        Alma N.  Mex. 

San  Gabriel 222     0.18               '06        Azusa Cal. 

Sangamon Illinois 5,592     111. 

San  Joaquin 1,637      Herndon Cal. 

San  Juan 1 ,320     Arboles Colo. 

San  Juan 6,920     0.035            '05        Farmington N.  Mex. 

San  Pedro 2,870     Dudleyville Ariz. 

Santa  Ana 182     0.26               '06        Mentone Cal. 

Santa  Ynez 207     0.005            '06        Santa  Barbara Cal. 

Santee 14,700     S.  C. 

Santiam,  North  Fork 740     1.00               '06         Mehama Oregon 

Santiam,  South  Fork 640     0.47               '06        Waterloo Oregon 

Saranac 624     0.498            '06        Plattsburg N.Y. 

Sauk Mississippi 968 

Savannah 2,712     Calhoun  Falls S.  C. 

Savannah 7,294     0.35           '04-'05     Augusta Ga. 

Savannah 10,000     S.  C.  and  Ga. 

Schoharie  Creek Mohawk 240    0.125            '06        Prattsville N.  Y. 

Schoharie  Creek Mohawk 684     Central  Bridge 

Schoharie  Creek Mohawk 930     Schoharie  Falls 

Schoharie  Creek Mohawk 947     Fort  Hunter N.  Y. 

Schroon..                           ..Hudson..  479  ....     Schroon  Lake 


POWER  OPPORTUNITY  23 

Drainage  Low 

River.                                Tributary  of  Area.  Flow.              Year.                             At                             State. 

Schroon Hudson 502     Tumblehead  Falls 

Schroon Hudson 556     Warrensburg N.  Y. 

Schuylkill Delaware 1,915     0.368            '05        Philadelphia Pa. 

Scioto Ohio 153     Kenton Ohio 

Scioto Ohio 1,051     0.039         '04-'05     Columbus Ohio 

Scioto Ohio 1,660     Shadesville Ohio 

Scioto Ohio 6,400     Ohio 

Sebasticook Kennebec 1,070     Me. 

Seneca Oswego 745     Waterloo 

Seneca Oswego .  771      Seneca  Falls 

Seneca Oswego 1,593     below  Cayuga  Lake 

Seneca Oswego 2,472     Monte/uma 

Seneca Oswego 3,101     0.605         '04-'05     Baldwinsville N.  Y. 

Seneca Oswego 3,447     N.  Y. 

Seneca Tubelo 646     1.07              '05        Clemson  College S.  C. 

Seneca Tubelo 908     S.  C. 

Sevier 255     Salina 

Sevier 3,986     0.0063          '05        Gunnison Utah 

Sevier 5,595     Leamington 

Shell  Rock Cedar 2,631      Iowa 

Shenandoah Potomac 2,624     Riverton Va. 

Shenandoah Potomac 2,850     Va.  and  W.  Va. 

Shenandoah Potomac 2,995     0.19           '04-'05     Millville W.  Va. 

Shenandoah,  South  Branch 1,288     Shenandoah 

Shenandoah,  South  Branch 1,491      Overall 

Shenandoah,  South  Branch 1,569     0.23           '04-'05     Front  Royal Va. 

Shenandoah,  North  Branch 215      Brocks  Gap 

Shenandoah,  North  Branch 511      Mt.  Jackson 

Shenandoah,  North  Branch 1 ,037     0.165            '05        Riverton Va. 

Shetucket Yantic 396     0.558         '04-'05     Willimantic Conn. 

Shetucket Yantic 1,245     Norwich Conn. 

Sheyenne , 5,400     0-009             '06        Haggart N.  Dak. 

Shoshone 1,480     0.12           '04-'05     Cody Wyo. 

Shoshone 1,718     Corbett 

Shoshone 2,720 Lovell Wyo, 

Shoshone,  South  Fork 500     0.212            '06        Marquette Wyo. 

Siletz 220     0.90               '06        Siletz ...Oregon 

Silver  Creek 221     0.06               '06        Silver  Lake Oregon 

Silvies 865     0.025             '06        Burns Oregon 

Skunk Mississippi 4,409     Iowa 

Smoky  Hill Republican 2,255     above  Ellsworth Kas. 

Smoky  Hill Republican 7,980     0.0047          '04        Ellsworth Kas. 

Smoky  Hill Republican 20,000 Kas. 

Snake Columbia 10,100     Idaho  Falls .Ida. 

Snake Columbia 17,900     0.109            '05        Minidoka Ida. 

Snake Columbia 22,600     Montgomery  Ferry 

Snake,  North  Fork 1,040     0.902            '06        Ora Ida. 

Snake,  South  Fork 820     0.458            '05        Moran Wyo. 

Snake,  South  Fork 5,480     0.376            '05        Lyon Ida. 

Solomon Smoky  Hill 5,539     Beloit 

Solomon Smoky  Hill 6,815     Niles 

Solomon Smoky  Hill 6,939 Kas. 

South Shenandoah 1,050     Pt.  Republic Va. 

South Ocmulgee 595     Ga. 

Spanish  Fork 670     0.001             '06        Spanish  Fork Utah 

Spearfish  Creek 230     0.35               '06        Spearfish S.  Dak. 

Spokane 4,000     0.40               '06        Spokane Wash. 


24  HYDRO-ELECTRIC   PRACTICE 

Drainage  Low 

River.                               Tributary  of  Area.  Flow.              Year.                            At                             State. 

Spoon Illinois 1,905     111. 

Stanislaus 935     0.20               '06        Knights  Ferry Cal. 

Staunton Dan 3,076     Randolph Va. 

Staunton Dan 3,450     Va. 

Staunton Dan 3,546     Clarksville Va. 

St.  Mary 452     0.21               '06        Cardston Alberta 

Stony  Creek 760     0.023             '06        Fruto Cal. 

Susquehanna 1,638     bel.  mouth  Unadilla 

Susquehanna 1,789     Nineveh 

Susquehanna 2,024     Susquehanna Pa. 

Susquehanna 2,279     Birmingham Pa. 

Susquehanna 2,400     0.294            '06        Binghamton N.  Y. 

Susquehanna 4,945     ab.  mouth  Chemung 

Susquehanna 7,463     bel.  mouth  Chemung 

Susquehanna 9,810    .0.46           '04-'05     Wilkesbarre Pa. 

Susquehanna 11,070     0.288            '06        Danville Pa. 

Susquehanna 24,030     0.395            '06        Harrisburg Pa. 

Susquehanna 26,800     0.47              '06        McCall  Ferry Pa. 

Susquehanna,  W.  Branch 5,640     0.43           '04-'05     Williamsport Pa. 

Susquehanna,  W.  Branch 6,538     Allenwood Pa. 

Susquehanna,  W.  Branch 7,027     mouth 

Sweetwater 2,929     mouth Wyo. 

Tallapoosa Coosa 2,500     0.20           '04-'05     Sturdevant Ala. 

Tallapoosa i Coosa 2,610     Susanne 

Tallapoosa Coosa 3,840     Milstead 

Tallapoosa Coosa 4,935     Ga.  and  Ak. 

Tar Pamlico 2,290     Tarboro 

Tar Pamlico 3,000     N.  C. 

Tennessee 8,990     0.30           '04-'05     Knoxville Tenn. 

Tennessee 21,418     0.30           '04-'05     Chattanooga Tenn. 

Teton 960     0.26               '06        St.  Anthony Ida. 

Teton 967     0.387            '05        St.  Anthony Ida. 

Thames 1,450     Conn.,  R.  I.,  Mass. 

Thornapple ....Grand 824     Mich. 

Thunder  Bay 580     ab.  North  Branch 

Thunder  Bay 789 ab.  South  Branch 

Thunder  Bay 1,267     0.294            '05        Alpena Mich. 

Thunder  Bay,  S.  Branch 454     Mich. 

Thunder  Bay,  N.  Branch 199     Mich. 

Tieton 289    0.80              '06        Naches Wash. 

Tiffin Maumee 723     Mich. 

Tiffin Maumee 748     0.064         '04-'05     Defiance Ohio 

Tiger Broad 720 

Tioga Susquehanna. . . .  750     Canisteo N.  Y. 

Tioga Susquehanna 1,530     Pa.,  N.  Y. 

Tioughnioga Susquehanna. . . .  428     Atselic 

Tioughnioga Susquehanna 735     N.  Y. 

Tioughnioga,  W.  Branch 103 

Tioughnioga,  E.  Branch 164 

Tippecanoe 1,890     0.279            '06        Delphi Ind. 

Toe Nolichucky 438     Huntdale N.  C. 

Tohickon  Creek Delaware 102     0.560            '06        Pt.  Pleasant Pa. 

Tombigbee Alabama 4,440     0.15           '04-'05     Columbus Miss. 

Tombigbee Alabama 8,830     0.190            '06        Epes Ala. 

Tombigbee .Alabama 21,917     Ala. 

Tongue 3,875     Miles  City Mont. 

Tonto  Creek Salt 1,030     Livingston Ariz. 


POWER   OPPORTUNITY  25 

Drainage  Low 

River.                                Tributary  of  Area.  Flow.  Year.  At                             State. 

Trinity 16,000  0.04  '04-'05     Riverside Tex. 

Truckee 502  0.040  '05        Tahoe Cal. 

Truckee 955  0.403  '05  Nev .-Cal.  State  line 

Truckee ; 991  mouth  Little  Truckee 

Truckee 1,014  Laughtono Nev. 

Truckee 1,519  0.167  '05        Vista Nev. 

Truckee '..  2,130  0.096  '05        Wadsworth Nev. 

Tuckaseegee 662  0.71  '04-'05     Bryson N.  C. 

Tugaloo 593  1.0  '04-'05     Madison Ga. 

Tugaloo 870  Ga.  and  S.  C. 

Tule 437  0.09  '06        Portersville Cal. 

Tuolomne 400  Hetch  Hetchy  Valley 

Dam  site 

Tuolomne 1,501  0.041  '05        Lagrange Cal. 

Tuolomne 1,635  Modesto Cal. 

Tygart's  Valley Monongahela 1,367 

Uinta 218  Whiterocks Utah 

Uinta 672  0.140  '04        Fort  Duchesne Utah 

Uinta 967  0.086  '04        Ouray  School Utah 

Umatilla Columbia 353  1.00  '06        Gibbon Oregon 

Umatilla 1,200  0.04  '06        Yoakum Oregon 

Umatilla 2,130  0.0005  '06        Umatilla Oregon 

Umpqua,  North  Fork 1,000  0.90  '06        Oakcreek Oregon 

Umpqua,  South  Fork 1,800  0.12  '06        Brockway Oregon 

Uncompahgre Gunnison 433  0.021  '04-'05     Colona Colo. 

Uncompahgre Gunnison 497  Ft.  Crawford 

Uncompahgre Gunnison 565  0.050  '05        Montrose Colo. 

Uncompahgre Gunnison 565  0. 10  '06        Montrose Colo. 

Uncompahgre Gunnison 1,130  0.010  '04-'05     Delta Colo. 

Upper  Iowa Mississippi 952  Minn. 

Verde 6,000  0.030  '04-'05     Ft.  McDowell Ariz. 

Verdigris Arkansas 3,067  McTaggart's  Mills Kas. 

Verdigris Arkansas 8,010  Kas.  and  I.  T. 

Vermilion Missouri 2,230  Dak. 

Vermilion Illinois 1,413  111. 

Wabash Ohio 3,163  0.273  '05        Logansport Ind. 

Wabash Ohio 12,200  0  22  '06        Terre  Haute Ind. 

Walker 2,420  0.024  '05        Wabuska Nev. 

Walker 306  0.26  '06        Coleville Cal. 

Walker,  East  Fork 1,100  0.09  '06        Yerington Nev. 

Walker,  East  Fork 1,103  0.052  '05        Yerington Nev. 

Walker,  West  Fork .• . .  .  306  0.199  '05        Coleville Cal. 

Walla  Walla 130  1.70  '06        Milton Oregon 

Wallowa 510  0.53  '06        Wallowa Oregon 

Wallowa 870  0.42  '06        Elgin Oregon 

Wapsipinicon Mississippi 1,308  0.127  '06        Stone  City Iowa 

Wapsipinicon Mississippi 2,568  Iowa 

Watauga 261  Butler Tenn. 

Watauga 408  0.475  '04-'05     Elizabethton Tenn. 

Weiser 1,670  0.046  '04        Weiser Ida. 

Wenatchee 1,190  0.90  '06        Cashmere Wash. 

West  Gallatin 860  0.40  '04-'05     Salesville Mont. 

White,  East  Branch 4,900  0.18  '04-'05     Shoals Ind. 

White,  West  Branch 1,520  0.23  '04-'05     Indianapolis Ind. 

White Arkansas 27,925  Ark.  and  Mo. 

White , .  Connecticut 680  0.309  '04        Sharon Vt. 

Willamette 4,860  0.69  '06        Albany Oregon 


HYDRO-ELECTRIC    PRACTICE 


River. 


Tributary  of 


Drainage     Low 
Area.        Flow. 


0.10 

0.60 

0.015 

0.018 

0.695 

1.10 

0.834 


0.97 


Willamette,  Coast  Fork 690 

Willamette,  Middle  Fork 1,450 

Willow  Creek 259 

Willow  Creek 455 

Winooski 885 

Wisconsin Mississippi 2,630 

Wisconsin Mississippi 5,800 

Wisconsin Mississippi 12,280 

Wood 906 

Wood 2,190 

Yadkin 500 

Yakima 1,960 

Yakima 3,300 

Yakima 5,230 

Yamhill 290 

Yampa 1,730 

Yampa Green 1,730 

Yampa Green 3,670 

Yazoo Mississippi 8,580 

Yazoo Mississippi 12,794 

Yellowstone 2,635 

Yellowstone 3,580 

Yellowstone 11,180 

Yellowstone 66,090 

Youghiogheny Monongahela 295 

Youghiogheny Monongahela 435 

Youghiogheny Monongahela 1 ,800     

Yuba 1,220     0.376 

Yuba,  North  Fork 483     

Yuba,  Middle  Fork 205     


Year. 
'06 
'06 
'06 


At 


State. 


'06 
'06 
'06 
'06 


Goshen Oregon 

Jasper Oregon 

Malheur Oregon 


'05 


0.210 

0.031 

0.28 

0.16 

0.072 

0.050 

0.159 


0.289 
0.240 
0.068 
0.160 
0.126 


Dell Oregon 

Richmond Vt. 

Merrill Wis. 

Necedah Wis. 

mouth Wis. 

Hailey Ida. 

Toponis Ida. 

North  Wilkesboro N.  C. 

Selah Wash. 

Yakima Wash. 

Kiona Wash. 

Sheridan Oregon 

Craig Colo. 

Craig Colo. 

Maybell Colo. 

Yazoo  City Miss. 

Miss. 

Harr Mont. 

Livingstone Mont. 

Billings Mont. 

Glendive Mont. 

Friendsville Md. 

'04-'05  Confluence Pa. 

Md.  and  Pa. 

'05  Smartville Cal. 

North  San  Juan Cal. 

North  San  Juan  . .  . .  Cal. 


'06 
'06 
'06 
'06 
'05 
'05 
'04 


'05 
'05 
'05 
'04 


ARTICLE  9. — The  topography  of  the  drainage  area  represents  the 
undulations  of  the  surface,  which  exercise  an  important  influence  upon  the 
distribution  of  run-off.  It  is  self-evident  that  the  storm  run-off  will  be 
greater  from  a  hilly  country  than  from  table-lands  and  that  the  part  of 
precipitation  remaining  available  for  ground  storage  will  be  correspond- 
ingly smaller;  the  topography,  therefore,  is  one  of  the  fundamental 
conditions  determining  constancy,  fluctuations,  and  flood  characteristics 
of  stream  flow  and  should  receive  commensurate  consideration. 

A  topographical  map  of  the  United  States  is  published  by  the 
United  States  Geological  Survey,  from  which  the  general  topography  of 
all  important  drainage  areas  can  be  readily  found, — that  is,  it  can  be 
learned  whether  the  area  is  generally  of  a  hilly  or  flat  country,  whether 
stream  channels  are  narrow  and  declivitous  or  broad  valleys,  and  what, 
if  any,  is  the  area  of  lakes  and  swamps.  It  is  not  necessary  to  define 
these  conditions  as  to  details,  but  it  is  essential  to  understand  the  pre- 
vailing features  as  distinguished  between  the  flat  land  drainage  areas  of 
streams  in  Iowa,  Illinois,  Indiana,  and  the  middle  West,  and  those  of 


POWER   OPPORTUNITY  27 

rolling  and  hilly  formation  in  Virginia,  Kentucky,  Vermont,  or  the  Pacific 
slope;  or  of  parts  of  a  river,  when  perhaps  a  site  on  its  upper  reach  is 
considered,  where  practically  all  of  the  area  is  in  mountain  ranges  or 
foot-hills,  or  a  point  near  the  mouth  of  the  river,  where  only  a  small 
part  of  the  area  is  in  hilly  and  by  far  the  greater  is  in  flat  or  roll- 
ing country. 

As  an  example,  the  Cumberland  River  may  be  cited,  of  which  Chart 
2  gives  drainage  areas  for  two  important  water-power  sites, — the  upper 
one  at  Cumberland  Falls,  Ky.,  often  called  the  Niagara  of  the  South,  the 
lower  one  near  Nashville,  Tenn. ;  the  first  is  almost  wholly  in  the 
mountain  region,  while  the  Nashville  site  area  is  largely  of  flat  and  roll- 
ing country. 

Such  general  information,  as  has  been  said  before,  can  be  gleaned 
from  the  United  States  Geological  Map  or  from  the  Map  of  Altitudes 
published  by  the  same  department.  Some  conclusions  as  to  topography 
can  frequently  be  drawn  from  location  of  railroads  and  highways,  espe- 
cially from  the  former,  which  in  hilly  and  broken  country  more  generally 
parallel  the  watercourses  than  in  flat  or  rolling  parts.  Many  sections 
have  been  covered  by  detail  topographical  surveys,  and  the  informa- 
tion then  is  conclusive. 

To  secure  a  sufficient  appreciation  of  the  topography  from  any  or 
all  of  these  sources  requires  considerable  experience  in  the  reading  of 
the  projections.  It  is,  of  course,  prohibitive  in  cost  to  make  surveys  for 
this  purpose,  but  a  horseback  reconnoissance  or  drifting  down  the  river, 
or  the  major  portion  of  it,  will  frequently  enable  the  investigator  to  form 
correct  conclusions  on  this  point.  The  author  has  examined  several 
rivers  by  going  down  in  a  canoe,  and  the  information  thus  gained  proved 
exceedingly  valuable  in  planning  power  developments. 

ARTICLE  10. — The  geology  of  the  drainage  area  should  be  understood 
to  the  extent  of  influencing  the  degree  of  absorption  and  storm  run-off. 
Where  rock  ledge  is  at  surface  or  crops  out  in  banks,  the  depth  of  over- 
lying drift  is  readily  ascertained;  otherwise  borings  should  be  made,  if 
practicable  to  rock,  and  the  character  of  the  overlying  material  found. 
The  percolosity  of  the  ground  determines  its  storage  capacity.  A  very 
satisfactory  conception  of  this  latter  can  be  obtained  from  the  observance 
of  conditions  following  heavy  rainfalls,  when  frequent  accumulations  of 
pools  of  water  in  level  fields  are  evidence  of  the  prevalence  of  non-absorb- 
ent soil,  while  its  rapid  disappearance  indicates  sandy  and  gravelly  for- 


28  HYDRO-ELECTRIC    PRACTICE 

mations.  The  stream  itself  gives  testimony  of  these  conditions,  the  water 
being  turbid  where  draining  clayey  soils,  while  the  run-off  from  porous 
earths  shows  little  discoloration.  No  practical  information,  for  the  inves- 
tigation in  hand,  can  be  gained  from  this  study  beyond  the  formation 
of  the  immediate  subsurface,  and  this  can  be  obtained  by  a  personal 
examination  of  the  locality  in  question  and  a  study  of  the  farming  culture. 
In  many  sections  conclusive  data  can  be  obtained  from  records  of  well 
borings,  which  are  generally  sunk  by  one  concern  covering  several  coun- 
ties. Some  of  the  State  Geological  departments  publish  such  records. 

ARTICLE  11. — The  flora  and  culture  in  the  drainage  area  constitute 
the  third  characteristic  which  influences  the  flow.  Forests  are  conservers 
of  water,  protecting  it  from  the  heat  of  the  sun  and  the  winds,  and  thus 
retarding  its  evaporation  as  compared  with  cultivated  fields,  grazing 
land,  or  open  soil,  while  the  many  obstructions  to  the  storm  run-off  in 
timbered  areas  result  in  a  greater  portion  finding  its  way  into  ground 
storage.  The  requirement  of  moisture  for  tree  growth  is  considerably 
less  than  that  of  crops;  for  instance,  long  grass  consumes  six  times  as 
much  water  as  fir  trees.  Wooded  hill-sides,  tamarack  and  cypress  swamps 
are  storage  reservoirs;  highly  cultivated  table-lands  with  tile  drainage 
leave  but  little,  if  any,  surplus  during  the  growing  season  for  run-off. 
It  is  important,  therefore,  to  secure  an  adequate  knowledge  of  these 
conditions.  The  degree  of  cultivation  can  be  ascertained  from  the  rural 
population  of  counties  and  the  character  and  volume  of  produce  shipped 
out,  all  of  which,  together  with  the  forest  area,  can  be  obtained  from 
the  United  States  census  publications. 

ARTICLE  12. — As  stated  before,  precipitation  is  the  source  of  all 
stream  flow,  which  latter  can  only  be  a  fraction  of  it.  Frequently  a  good 
enough  preliminary  estimate  of  flow  can  be  made  if  quantity  of  precipi- 
tation in  drainage  area  and  the  extent  of  the  latter  which  contributes  to 
the  river  at  the  point  under  examination  are  known,  and  reliable  data 
of  fluctuations  of  flow  throughout  seasons  and  years  can  be  found  from 
such  information. 

Drainage  areas,  as  has  been  seen,  can  be  readily  measured,  and 
precipitation  is  ascertainable  from  public  records.  For  fifty  years  and 
longer  rain-  and  snow-fall  have  been  measured  in  the  United  States  and 
Canada  through  the  agency  of  the  Government,  in  this  country  by  the 
United  States  Weather  Bureau,  in  the  Dominion  of  Canada  by  Provincial 
meteorological  departments;  points  of  observations  are  distributed  over 


30  HYDRO-ELECTRIC   PRACTICE 

the  country  with  somewhat  of  a  uniformity,  and  one  or  more  of  them 
can  always  be  found  in  a  certain  drainage  system.  The  measurements 
are  made  by  means  of  standard  cups,  so  exposed  that  they  receive  the 
normal  rain-  and  snow-fall,  which  is  measured  as  to  its  depth  in  inches 
and  fractions,  the  snow  being  melted  for  that  purpose  and  therefore  ex- 
pressed in  the  same  quantity  as  the  rain.  Observations  are  made  daily 
of  the  rain-  or  snow-fall  during  twenty-four  hours,  and  the  daily,  monthly, 
and  annual  totals  are  given  in  public  records. 

Such  measurements  require  no  skill  and  may,  therefore,  be  accepted 
as  a  fairly  accurate  record  of  precipitation. 

From  these  data  the  general  distribution  of  precipitation  is  well 
known;  it  is  illustrated  on  Chart  3,  on  which  equi-precipitation  curves 
are  projected,  the  precipitation  being  the  normal  annual  quantity  in 
inches.  This  may  be  used  with  advantage  for  first  investigations  of 
stream  flow,  exhibiting  neither  the  wet  nor  dry  but  the  normal  year. 

Observations  of  this  character  have  been  carried  on  for  a  sufficiently 
continuous  period  to  warrant  the  conclusion  that  precipitation  is  not 
undergoing  any  great  changes :  it  does  not  rain  more  or  less  now  than  it 
did  fifty  years  ago,  nor  does  the  clearing  of  land  seem  to  be  followed  by 
any  marked  change  in  rainfall  in  that  section.  The  ordinary  fluctuations 
of  precipitation  appear  to  be  represented  in  a  cycle  of  seven  years, — that 
is,  the  totals  of  seven  years  of  precipitation  are  very  nearly  equal;  each 
of  these  seven-year  periods  contains  one  dry  year,  the  one  of  least  precipi- 
tation, and  generally  one  or  two  extremely  wet  years. 

ARTICLE  13. — The  information  to  be  sought  in  connection  with 
determination  of  stream  flow  comprises  the  quantity  and  distribution  of 
rain  and  snow  during  at  least  one  complete  cycle  of  seven  years,  in  order 
to  fix  upon  the  ordinary  dry  year  of  the  period.  The  safe  method  is  to 
collect  the  precipitation  data  by  monthly  totals  from  as  many  observa- 
tion points  as  are  obtainable  in  the  drainage  area  for  a  period  of  fifteen 
continuous  years,  which  are  certain  to  contain  a  complete  cycle.  If  the 
entire  drainage  area  is  located  in  the  same  precipitation  belt  as  per  Chart 
3,  the  monthly  means  of  all  observations  are  compiled  and  may  be  taken 
as  applying  to  the  entire  area;  when  the  drainage  area  extends  through 
different  precipitation  belts,  the  monthly  means  of  stations  in  each 
precipitation  belt  are  to  be  found,  the  drainage  area  is  to  be  divided  into 
parts  covered  by  different  precipitation  belts,  and  the  respective  monthly 
means  applied  to  each.  Such  precipitation  records  from  five  points  in 


121    119    117    115    113     111    r<>9    107    105    103    101     99 


B5  83          81  79 


POWER   OPPORTUNITY 


31 


drainage  area  of  Green  River,  Ky.,  for  fifteen  years  by  monthly  means, 
which  in  the  case  of  this  system,  lying  in  the  same  precipitation  belt, 
may  correctly  be  accepted  for  the  whole  area,  are  here  given. 

PRECIPITATION  IN  GREEN   RIVER,   KY.,    DRAINAGE   AREA   FROM   1891   TO   1905, 

BY  MONTHLY  MEANS. 


Station. 

1891 

Jan. 
680 

Feb. 
7.61 

March 
8.24 

April 
2.42 

May 
0.76 

June 
3.02 

July 

1.08 

Aug. 
6.76 

Sept. 
2.41 

Oct. 
0.96 

Nov. 
6.56 

Dec. 

4.37 

Total. 

50.99 
52.73 
45.56 

52.61 
44.86 

51.59 
50.95 
51.70 

35.35 
39.41 
37.73 

44.44 
40.94 
40.72 

46.85 
45.73 
47.59 
41.50 

39.26 

43.54 

53.39 
48.94 
51.35 

58.73 
54.05 

48.04 
52.50 
50.59 
48.40 
43.95 

Edmonton          .  . 

.  .  .   5.77 

6.84 
6.80 

2.60 
3.04 
2.62 

4.26 
4.67 
4.61 

6.37 
5.47 
5  14 

9.46 

8.83 

5.48 
4.79 
3.52 

3.29 
3.66 
3.63 

2.72 
2.70 
3.26 

2.61 
2.05 

10.84 
8.56 
8.15 

7.12 
5.10 
5.61 

3.59 
3.33 
2.71 

0.97 
0.65 

6.64 
4.97 
4.92 

8.67 
8.63 
5.44 

3.47 
4.18 
3.14 

6.71 
4.07 

4.35 
3.78 
2.67 

5.87 
6.46 

8.52 

0.93 
1.79 
3.59 

2.15 

2.38 

1.19 
2.58 
4.02 

5.85 
5.29 
6.02 

3.84 
2.54 
2.97 

6.27 
4.84 

2.57 
5.29 

1.37 
2.09 
3.26 

2.98 
4.62 
4.75 

1.41 
2.30 

4.12 
3.20 

2.74 
3.54 
3.21 

3.28 
3.91 

2.64 

0.94 
1.31 

0.10 
0.41 
0.10 

4.88 
3.08 
4.46 

0.83 
1.22 
1.25 

6.22 
5.22 

4.39 
4.30 
3.80 

4.03 
3.63 
2.83 

1.41 
2.13 
1.42 

3.38 
3.15 

7.73 
5.50 
4.53 

2.79 
3.42 
3.47 

2.84 
4.21 
3  94 

Grecnsburg       .  .  . 

.  .  .   4.96 

1892 
Bowling  Green 

...   2.60 

Edmonton  
Greensburg  

.  ..    2.42 
.  .  .   2.04 

1893 
Bowling  Green 

.  ..  0.72 

Edmonton   

.  .  .    1.38 

Greensburg  

.  .  .   0.64 

1894 
Bowling  Green.  .  . 

.  ..   3.09 

Edmonton  

.  ..   3.31 

292 

1895 
Bowling  Green.  .  . 

.  ..   5.28 

0.47 

0.84 
0.81 

3.26 

3.87 
3.86 
3.35 

3.54 

4.46 
4.39 

6.92 
7.56 
6.90 
5.47 
4.92 

7.61 

2.82 
3.09 
3.32 

3.67 
2.52 
1.25 
0.78 
0.43 

7.45 

5.42 
4.46 
2.18 

5.71 
5.24 
4.30 
6.41 
5.04 

2.43 

1.96 
2.03 
5.10 

3.94 

3.48 
8.47 
2.87 
3.10 

0.80 

9.95 
5.35 
4.85 

8.21 
8.27 
9.32 
6.58 
5.00 

2.98 

3.63 
1.79 
2.38 

1.48 
3.21 
1.85 
1.25 
1.25 

2.30 

0.67 
1.18 
0.25 

3.82 
3.28 
3.60 
3.54 
3.60 

0.08 

1.45 
2.69 
2.06 

1.32 
0.74 
0.99 
1.41 
1.48 

0.80 

4.08 
3.42 
3.73 

5.42 
5.12 
4.71 
5.47 
4.68 

3.15 

5.17 
6.06 
4.92 

1.70 
1.63 
1.64 
3.06 
3.02 

376 

Edmonton  

.  .  .   5.57 

Greensburg 

.  .  .   6.73 

1896 
Bowling  Green 

1.40 

Edmonton 

.  .  .   0.81 

Greensburg 

.  .  .   0.70 

Leitchfield 

.  ..    1.31 

St  John 

1897 
Bowling  Green 

3.34 

4.56 

Edmonton 

.  .  .   2.87 

7.64 

8.10 

6.57 

1.88 

2.08 

4.90 

2.40 

0.82 
0.78 
1.38 
1.65 

4.95 
5.25 
6.65 
5.14 
3.50 

1.57 
2.22 
2.18 
2.04 
2.61 

3.74 
3.77 
4.35 
4.46 

3.22 

2.87 
2.77 
3.08 
2.57 

1.83 
1.68 
1.94 
2.75 
1.75 

3.80 
3.78 
3.48 
3.62 

2.96 
2.87 
3.85 
2.94 
2.76 

4.86 
5.44 
4.88 
4.74 
4.77 

Greensburg 

,  ..  3.62 

6.10 

8.22 

7.16 

5.04 

3.21 

4.90 

4.00 

Leitchfield 

3.36 

6.66 

9.62 

5.72 

3.10 

1.84 

2.86 

3.70 

St  John  

.  ..   3.41 

5.60 

0.82 
1.49 
1.26 
1.09 
1.26 

4.14 
6.33 
4.59 
3.68 
3.32 

8.92 

7.44 
5.96 
6.85 
9.27 
9.36 

8.65 
10.73 
10.32 
8.09 
7.65 

5.11 

4.08 
3.21 
3.21 
4.25 
4.20 

4.14 
4.42 
4.02 

3.88 
4.02 

3.39 

4.75 
2.50 
4.06 
5.83 
4.75 

4.83 
4.61 
6.16 
5.01 
4.05 

3.31 

3.87 
5.45 
1.75 
4.34 
5.05 

1.93 
2.67 
3.82 

2.84 
1.98 

2.71 

2.19 
3.15 
4.94 
4.35 
2.31 

5.26 
5.45 
3.16 
3.32 
2.45 

1.33 

3.80 
2.04 
1.81 
1.59 
3.22 

2.61 
1.54 
1.26 
3.78 
4.61 

0.03 

3.32 
3.62 
4.90 
6.12 
5.35 

0.71 
1.23 
0.92 
1.07 
0.86 

1898 
Bowling  Green 

...11.99 

Edmonton  

.  .  .  10.53 

Greensburg  

.  .  .   9.30 

Leitchfield 

.  .  .  10.73 

St  John         .... 

.  .  .   9.72 

1899 
Bowling  Green 

..  7.51 

Edmonton     .... 

.  .  .   6.18 

Greensburg  

.  .  .   7.34 

Leitchfield  

.  .  .  7.20 

St.  John.  . 

.   5.88 

HYDRO-ELECTRIC   PRACTICE 


Station. 


Jan.      Feb.     March    April      May     June      July       Aug.     Sept.      Oct.      Nov.      Dec.      Total, 


1900 

Bowling  Green  ......  3.15 

Edmonton  .........  2.26 

Greensburg  .........  2.16 

Leitchfield  .........  3.06 

St.  John  ...........  2.98 

1901 

Bowling  Green  ......  2. 

Edmonton  .........  2.31 

Greensburg  .........  1.99 

Leitchfield  .........  1.99 

St.  John  ...........  1.57 

1902 

Bowling  Green  ......  8.25 

Edmonton  .........  7.37 

Greensburg  .........  7.54 

Leitchfield  .........  6.61 

St.  John  ...........  5.65 

1903 

Bowling  Green  ......  2.64 

Edmonton  .........  2.25 

Greensburg  .........  2.69 

Leitchfield  .........  2.55 

St.  John  ...........  2.44 

1904 

Bowling  Green  ......  2.93 

Edmonton  .........  3.81 

Greensburg  .........  3.34 

Leitchfield  .........  3.32 

St.  John  ...........  2.99 

1905 

Bowling  Green  ......  3.21 

Edmonton  .........  2.84 

Greensburg  .........  3.12 

Leitchfield  .........  2.70 

St.  John  ...........  2.60 


5.30  2.74  2.60 

4.78  3.97  2.71 

4.85  3.63  2.68 

6.48  2.09  3.33 

5.59  2.37  2.56 


4.01  5.67  5.72 

2.66  7.14  6.27 

3.44  9.94  6.43 

4.58  3.79  3.32 

3.25  4.46  4.45 


1.67  4.41  2.65  10.94  3.17 

3.73  3.01  1.22  10.05  3.09 

4.31  1.66  1.23     6.85  3.21 

3.21  1.34  2.91  11.06  3.21 

4.57  1.37  2.25     8.81  2.79 


:.13 
'31 

1.15 
1.11 

3.36 
3.81 

3.90 
5.36 

1.31 
2.69 

2.71 

4.57 

0.17 
0.40 

7.34 
7.31 

5.38 
5.66 

0.62 
1.15 

1.25 
1.32 

5.60 
480 

.99 

qq 

0.93 
1.14 

3.23 
4.21 

4.30 
3.57 

2.35 
2.35 

4.19 
2.65 

1.55 
1.12 

3.66 
5.80 

3.87 
6.49 

0.97 
0.89 

1.03 
1  10 

4.35 
525 

.57 
;  ?5 

1.08 
1.39 

4.02 
6.18 

2.22 
2.68 

2.65 
3.82 

3.98 
3.22 

1.30 
0.72 

3.86 
2.53 

4.15 
4.35 

0.79 

2.78 

1.12 
4.49 

4.95 
9.24 

.37 

'  54 

1.40 
0.60 

7.03 
4.80 

2.86 
2.02 

2.77 
2.42 

2.77 
3.46 

3.31 

4.27 

1.78 
2.18 

4.96 

4.88 

2.57 
3.07 

4.29 
5.05 

9.82 
882 

i.61 
i.65 

0.89 
0.85 

3.91 
3.67 

3.31 
2.14 

2.94 
3.73 

5.51 
5.16 

0.89 
1.17 

2.15 
4.04 

8.25 
8.26 

1.04 
1.36 

4.45 
4.67 

11.97 
7.19 

8.37 
8.65 
8.48 
8.19 
7.94 

2.61 
2.45 
2.05 
2.34 
3.13 

1.96 
2.53 
2.05 
2.23 
2.31 


3.10 
6.67 
6.01 
3.78 
3.64 

5.00 
7.27 
5.52 
6.85 
6.09 

3.53 
5.15 
5.59 
4.67 
4.66 


3.23 
5.35 
4.22 
3.93 
3.16 

2.46 
2.62 
2.78 
3.67 
2.98 

2.16 
2.46 
2.99 
3.33 
3.55 


4.95  5.95  5.46 

3.69  4.28  5.63 

4.27  3.84  3.02 

4.65  5.43  4.33 

3.86  3.94  2.30 

2.32  5.50  4.09 

4.17  2.35  4.26 

2.50  2.47  2.84 

1.37  6.03  2.49 

3.50  3.25  2.75 

3.39  4.22  3.65 

4.31  5.59  6.53 

3.81  3.69  6.03 

6.65  5.52  5.32 

5.74  4.85  5.93 


2.03  0.76  2.63  1.21  3.57 
2.19  0.35  3.01  3.89  3.02 
5.25  0.35  3.11  3.39  3.08 
3.95  1.35  1.48  2.97  3.38 
4.50  0.30  1.57  4.45  2.54 

2.41  2.24  0.05  1.40  5.40 

2.92  1.48  0.30  1.34  4.98 

5.48  2.66  0.16  1.06  4.67 

1.28  4.33  0.20  0.40  5.14 

1.12  2.49  0.21  0.57  5.46 

1.19  3.00  3.34  2.23  3.55 

2.58  4.45  4.92  3.52  4.72 

4.04  6.13  5.33  2.94  4.68 
2.00  3.90  4.16  3.53  5.22 
2.16  1.90  5.80  3.19  5.13 


52.03 
50.89 
50.39 
48.38 
45.45 

34.92 
40.49 
32.42 
36.56 
31.69 

49.65 
50.93 
49.11 
51.92 

47.89 

43.90 
48.91 
47.71 
45.99 
40.64 

36.41 
37.95 
35.53 
37.42 
34.54 

35.43 
49.62 
50.40 
49.23 

47.82 


The  annual  totals  are  plotted  as  shown  on  Profile  1,  from  which  the 
fluctuations  are  readily  appreciated,  the  year  1901  being  unmistakably 
the  dryest  of  the  period.  This  is  the  year  we  are  concerned  with,  and  by 
plotting  the  monthly  precipitation  as  shown  on  Profile  2  we  see  how  it 
was  distributed  and  which  are  the  months  of  low  flow. 

This  closes  the  necessary  precipitation  investigation,  the  dry  year 
has  been  found,  the  low  flow  months  are  known,  and  it  remains  to  be 
determined  what  portion  of  this  precipitation  evaporates,  which  will 
leave  the  quantity  representing  the  run-off  and  thus  the  flow. 

ARTICLE  14.  Evaporation. — Investigations  have  been  carried  on  in 
this  country  and  abroad  for  many  years  with  the  object  of  finding  a 


POWER   OPPORTUNITY 


33 


practical  method  for  evaporation  determination,  and  observations  and 
measurements  of  evaporation  from  water  surfaces,  forests,  uncultivated 
lands,  and  fields  with  growing  crops  of  all  kinds  have  conclusively  estab- 
lished such  a  ratio.  Evaporation  from  water  surfaces  is  found  by  aid  of 
evaporation  pans  which  are  of  considerable  area  and  water-tight,  the 
contents  of  which  may  be  found  precisely  at  known  intervals  of  time, 
the  diminution  being  due  to  evaporation.  For  this  determination  from 
land,  known  areas  are  isolated,  surrounded  by  ditches  in  which  the 
water  draining  off  can  be  accurately  measured,  when  the  difference 
between  the  quantity  of  a  certain  rainfall  and  that  draining  off  by  these 
ditches  represents  evaporation  from  that  area  for  a  given  time,  other 
climatological  conditions  being  duly  observed.  These  experiments  have 
been  repeated  in  various  latitudes  by  different  persons,  and  from  them 
certain  evaporation  values  have  been  determined. 

Table  2  gives  monthly  evaporation  in  inches  from  different  surfaces 
for  certain  locations. 


TABLE  2 

.*—  EVAPORATION 

FROM 

WATER  AT  EMDRUP,  DENMARK. 

(Latitude,  55° 

41'  N.; 

longitude,  12°  34'  E.  from  Greenwich.) 

Year. 

Jan. 

Feb. 

Mch. 

Apl. 

May. 

June. 

July. 

Aug. 

Sept. 

Oct. 

Nov. 

Dec. 

Total. 

in. 

in. 

in. 

in. 

in. 

in. 

in. 

in. 

in. 

in. 

in. 

in. 

in. 

1849  .  . 

..1.1 

0.3 

1.8 

2.5 

4.1 

5.8 

4.7 

4.0 

2.6 

1.1 

0.9 

0.6 

29.5 

1850  .  . 

..1.1 

0.3 

1.2 

1.7 

4.5 

5.6 

4.8 

4.8 

2.4 

1.6 

0.9 

0.2 

29.1 

1851  .  . 

..0.5 

0.4 

0.7 

1.7 

4.2 

4.8 

5.7 

5.1 

2.7 

1.5 

0.6 

0.5 

28.4 

1852  .  . 

..0.7 

0.5 

0.8 

2.4 

3.8 

4.6 

6.4 

4.5 

2.7 

1.7 

0.8 

0.5 

29.4 

1853  .  . 

..0.5 

0.1 

0.7 

1.0 

4.1 

6.2 

5.1 

4.2 

2.8 

1.1 

0.6 

0.5 

26.9 

1854  .  . 

.  .0.5 

0.9 

0.9 

3.2 

3.3 

4.5 

5.2 

•  4.3 

2.6 

1.2 

0.7 

0.6 

27.9 

1855  .  . 

..1.0 

1.1 

0.5 

1.2 

2.6 

4.1 

4.7 

4.1 

2.8 

1.4 

0.9 

0.7 

25.1 

1856  .  . 

..0.5 

0.5 

1.2 

2.1 

2.8 

4.6 

4.3 

4.0 

2.0 

1.9 

0.6 

0.5 

24.0 

1857  .  . 

..0.7 

0.6 

0.6 

1.4 

4.1 

6.6 

5.9 

4.3 

3.2 

1.4 

0.7 

0.4 

29.9 

1858  .  . 

..0.4 

0.7 

1.2 

3.1 

5.1 

6.1 

4.9 

5.6 

2.8 

1.6 

0.7 

0.4 

30.6 

1859  .  . 

..0.3 

0.5 

0.7 

1.9 

4.3 

5.8 

5.3 

3.8 

1.8 

1.0 

0.7 

0.3 

26.4 

Mean.... 0.7         0.5         0.9         2.0         3.7         5.4         5.2         4.4         2.6         1.3         0.7         0.5         27.9 
Ratio...    .301       .215       .387       .860     1.592     2.323     2.237     1.892     1.118       .559       .301       .215 


Mean  Evaporation  from  Short  Grass,  1852  to  1859,  inclusive. 


Mean 0.7 


Mean 0.9 


Mean. ...  1.5 


1.2 


2.6 


4.1 


5.5 


4.7 


2.8 


1.3 


0.7         0.5 


Mean  Evaporation  from  Long  Grass,  1849  to  1856,  inclusive. 


0.6 


1.7 


1.4 


2.6 


4.7 


6.7 


9.3 


7.9 


5.2 


2.9 


Mean  Rainfall  at  same  Station,  1848  to  1859,  inclusive. 
1.0         1.6         1.5         2.2         2.4         2.4         2.0         2.3 


1.3 


1.8 


0.5 


1.5 


30.1 


44.0 


21.9 


*  J.  T.  Fanning,  Water-Supply  Engineering. 


34  HYDRO-ELECTRIC   PRACTICE 

EVAPORATION  FROM  WATER-SURFACE  AT  BOSTON,  MASS.,  IN  INCHES— FOURTEEN 

YEARS*,— 1875-1890. 

1876.  1877.  1878.     1879.     1880.  '81-'84.  1885.    1886.  1887.     1888.    1889.  Total.  Mean. 

January 0.96  0.96  0.96  0.96  0.96  0.96  0.96  0.96  0.96  0.96  0.96  15.36  0.96 

February 1.05  1.05  1.05  0.15  1.05  1.05  1.05  1.05  1.05  1.05  1.05  16.80  1.05 

March 1.70  1.70  1.70  1.70  1.70  1.70  1.70  1.70  1.70  1.70  1.70  27.20  1.70 

April 2.98  2.98  2.98  2.98  2.98  2.98  2.98  3.12  3.07  2.78  2.84  47.57  2.97 

May 4.45  4.05  4.14  5.89  5.22  4.45  3.77  4.45  4.83  3.35  4.57  71.42  4.46 

June 5.44  5.68  5.26  5.32  6.46  5.55  7.01  5.25  5.05  5.98  3.94  88.69  5.54 

July 7.50  4.82  6.04  6.41  5.82  5.98  7.09  5.59  5.96  5.57  5.04  95.72  5.98 

August 6.21  4.40  4.33  5.23  5.34  5.50  7.41  5.80  6.20  5.81  4.25  87.98  5.50 

September 3.48  4.08  4.04  3.80  4.04  4.20  5.13  4.55  4.57  3.91  3.08  65.88  4.12 

October 3.12  2.51  3.52  2.99  2.79  3.11  2.79  4.13  3.61  3.27  3.13  50.52  3.46 

November 0.66  2.23  2.23  2.23  2.60  2.23  2.23  2.69  3.00  2.71  1.98  35.94  2.25 

December 1.51  1.51  1.51  1.51  1.51  1.51  1.51  1.51  1.51  1.51  1.51  24.16  1.51 

Total 39.06  35.97  37.76  40.07  40.47  39.22  43.63  40.80  41.51  38.60  34.05  627.24  39.20 

Evaporation  from  an  entire  drainage  area  of  a  stream  is  readily 
determined  if  precipitation  and  flow  for  a  sufficiently  continuous  period— 
as,  for  instance,  one  year — are  known.  Precipitation  may  be  measured 
as  already  described,  while  the  actual  quantity  of  water  passing  down 
the  stream  may  also  be  found  by  physical  measurements.  This  has  been 
done  on  many  streams  for  long  periods,  measuring  weirs  have  been 
erected  and  the  overflow  recorded  by  automatic  gauges,  and  thus  the 
continuous  and  total  flow  per  day,  month,  or  year  determined;  the 
difference  between  this  flow  and  the  total  precipitation  is  chargeable  to 
evaporation. 

From  such  data,  resulting  from  extensive  systematic  investigations, 
rules  have  been  evolved  to  find  evaporation,  the  correct  application  of 
which  will  give  results  in  harmonious  agreement  with  those  found  by 
measurements,  and  these  rules  or  formulae  may  be  applied  to  any  set 
of  conditions  for  the  purpose  of  finding  similar  results. 

A  detailed  description  of  the  method  of  determining  evaporation 
will  be  found  in  Part  II.;  a  practical  application  of  it,  from  the  author's 
practice,  will  go  far  toward  securing  for  its  further  study  that  degree  of 
confidence  in  its  value  for  the  general  investigation  of  stream  flow  which 
it  deserves. 

Green  River,  Ky.,  was  the  subject,  the  development  of  power  to  be 
planned  at  a  Government  lock.  The  drainage  area  was  delineated  from 
a  State  map,  as  shown  on  Chart  1 ;  precipitation  data  were  collected  as 

*  Desmond  Fitzgerald,  C.E.,  Rainfall,  Flow  of  Streams,  and  Storage.  (Transactions  Am.  Soc. 
C.  E.,  Vol.  XVII.) 


45 


40 


35 


Annual  Precipitation 
Green  river,  Ky. 


35 


3.0 

3.« 

2.5 
2.0 
1.5 
1.0 

2.5 
2.0 

1.0 
0.5 

/ 

IP 

$?F/  — 

\\  — 

S 

Monthly  Run  -  off 
Measured  &  computed 

Cjr 

/ 

\  \ 

/ 

^^  • 

/ 

"^^       \ 

/ 

1>          * 

\ 

/ 

*jl 

. 

\ 

x^ 

/ 

fM 

\ 

—  X 

=^  — 

^t 

-v— 

7 

i____\_ 

""""**«- 

^-^^' 

^^^ 

=^= 

===i— 

0.5 

H.E.P.6. 
H.vA 


35 


36  HYDRO-ELECTRIC   PRACTICE 

given  on  Table  3  and  on  Profiles  1  and  2 ;  from  these  evaporation  and 
run-off  were  computed,  the  results  for  the  latter  being  plotted  on  Profile 
3,  in  heavy  line,  as  monthly  run-off  for  the  dry  year  of  the  period  covered 
by  precipitation  records. 

The  overflow  at  the  Government  dam  had  been  recorded  daily  for 
this  same  year,  and  from  these  the  flow  was  computed  from  the  weir 
formula,  and  these  results  are  also  plotted  on  profile  in  light  line.  Both 
of  these  operations  were  executed  by  different  persons.  The  agreement 
between  the  two  profiles  is  striking,  the  discrepancies  during  the  winter 
months  are  accounted  for  by  the  fact  that  the  run-off  as  computed  was 
partially  frozen  and  therefore  retained  until  spring.  The  reliability  of 
the  computation  method  is,  however,  evident.  Similar  results  can  be 
quoted  from  published  records,  especially  in  New  England  and  Eastern 
States,  where  the  flow  of  many  streams  has  been  measured  in  similar 
manner  for  many  years  and  the  run-off  as  computed  from  evaporation 
compared  with  it.  In  fact,  the  system  has  been  evolved  from  compara- 
tive results  on  rivers  where  flow  has  been  established  by  physical  measure- 
ments. The  author  has  always  used  the  two  methods  of  calculation  and 
measurements  to  check  results  whenever  authentic  flow  measurements 
covering  sufficient  periods  were  available,  and  has  found  them  to  agree 
most  satisfactorily. 

ARTICLE  15. — The  application  of  flow  deductions  from  precipitation 
for  preliminary  investigation  purposes  is  expressed  by  the  following  rules : 

Rule  1.  About  30  per  cent,  of  annual  precipitation  remains  avail- 
able for  flow;  the  other  portion  is  evaporation. 

Rule  2.  The  low  monthly  flow  cannot  exceed  one- twelfth  of  the 
total  available  flow. 

Rule  3.  The  monthly  flow  during  three  months,  generally  in  the  fall, 
in  Northern  latitudes  is  from  one-half  to  one-third,  in  Southern 
latitudes  from  one-fourth  to  one-sixth,  and  in  Western  States 
from  one-sixth  to  one-tenth  of  one-twelfth  of  the  annual  pre- 
cipitation excess  over  evaporation. 

The  author  has  met  cases  where  the  application  of  this  simple  rule 
would  have  saved  to  the  promoters  of  water-power  projects  thousands 
of  dollars.  One  in  point  is  recalled,  where  a  water-power  was  projected 
on  a  stream  with  a  drainage  area  of  about  700  square  miles,  the  avail- 
able fall  was  30  feet,  and  the  opportunity  was  credited  with  a  power 
output  of  3500  horse-power,  which  would  call  for  an  available  flow  of 


POWER   OPPORTUNITY  37 

about  1450  cubic  second  feet,  requiring  run-off  of  2.07  cubic  second  feet 
per  square  mile  of  area,  which  represents  monthly  precipitation  excess 
over  evaporation  of  2.3  inches.  These  facts  should  be  sufficient  to  reveal 
a  gross  error  in'  the  assumed  power  output, — that  is,  if  the  area  has  been 
ascertained.  The  stream  was  in  a  Northern  State  where  normal  annual 
precipitation  is  35  inches,  annual  temperature  about  48°,  and  annual 
evaporation  therefore  nearly  the  same  as  that  found  in  the  example 
given,  or  about  seven-tenths,  leaving  a  residue  of  precipitation  for  annual 
run-off  of  about  three-tenths,  or  eleven  inches  for  the  entire  year.  As  a 
matter  of  fact,  the  opportunity  was  good  for  about  1500  horse-power 
with  a  250  horse-power  auxiliary  plant  supplementing  the  three  months 
low  flow  output.  About  1000  acres  of  lands  had  been  purchased  and 
paid  for,  but  no  power  development  has  yet  taken  place.  Many  similar 
instances  could  be  cited. 

ARTICLE  16. — Flow  measurements  are  made  by  various  methods,  but, 
unless  they  extend  over  a  sufficiently  long  period,  especially  covering  the 
low  stages,  their  result  is  not  conclusive  as  to  the  available  flow.  As  a 
rule,  the  time  necessary  to  do  this  properly  cannot  be  taken ;  when  water- 
power  projects  ripen  to  the  stage  of  such  investigations,  results  are 
expected  promptly,  and,  unless  it  is  then  the  period  of  low  flow,  measure- 
ments will  be  of  little  practical  value.  On  many  streams  measurements 
have  now  been  made  for  several  years  by  the  Federal  Government,  the 
results  being  published  in  annual  reports  of  United  States  Geological 
Survey  as  stream  measurements,  and,  where  these  have  been  carried  on 
long  enough  to  furnish  a  rating  table  for  the  stream,  this  information 
may  be  taken  as  conclusive  for  the  purpose.  Table  1  gives  low  flow  for 
some  rivers  in  the  United  States  compiled  from  this  source. 

The  most  reliable  method  of  measuring  a  stream's  flow  is  by  an 
overflow  weir,  which  is  a  type  of  low  dam  over  which  the  entire  flow 
passes.  It  is,  of  course,  necessary  that  no  portion  of  the  flow  passes 
under  it  or  around  its  ends,  and  this  is  neither  readily  nor  economically 
constructed,  and,  as  a  rule,  is  impracticable  unless  the  stream  is  a  very 
small  one.  If  the  river  is  already  crossed  by  a  dam,  it  may  afford  a 
satisfactory  opportunity  for  measurement,  provided  it  is  free  from  leaks 
and  its  crest  is  horizontal.  Old  mill-dams  are  generally  not  water-tight 
and  are  more  or  less  out  of  alignment,  and  therefore  not  very  reliable 
for  this  purpose. 

The  technic  of  weir  measurements  and  reductions  is  described  in 


38  HYDRO-ELECTRIC    PRACTICE 

detail  in  Part  II.,  Chapter  6;  for  practical  purposes  of  first  investiga- 
tions, the  following  method  will  yield  sufficient  results.  Ascertain  the 
length  of  dam  crest  by  stadia  measurement  or  triangulation,  and  the 
height  of  overflow  by  differential  levels  between  water  surface  some 
thirty  feet  upstream  of  the  dam  and  of  dam  crest,  and  take  correspond- 
ing flow  from  Diagram  2,  which  gives  the  volume  passing  per  linear  foot 
of  overfall  over  a  wide  flat-crested  dam  in  cubic  second  feet  for  depths 
of  overflow  in  tenths  of  inches. 

Example. — Overflow  of  1.2  inches  over  dam  crest  236  feet  long  repre- 
sents a  flow  of  4.35  cubic  second  feet. 

Mill-dams,  unless  in  very  bad  condition,  may  furnish  valuable  data 
as  to  flow;  millwrights  know  how  much  power  is  required  to  operate 
their  plant,  the  effective  head  can  readily  be  measured,  and,  crediting 
the  water-wheels  with  an  efficiency  of  about  65  per  cent,  when  of  old 
pattern,  the  volume  passing  through  them  can  be  computed.  Nothing 
is  more  strongly  impressed  upon  the  miller  than  shortage  of  water  and 
the  length  of  time  during  which  he  has  to  shut  down  to  raise  the  pond, 
and  the  depth  below  the  dam  crest  to  which  the  pond  lowers  during 
low  seasons  after  running  the  mill  a  certain  period;  each  one  of  these 
facts  may  be  utilized  in  determining  the  low  flow  of  the  stream  and  its 
duration. 

The  author  determined  the  low  flow  on  the  Cannon  River,  Minn., 
in  1904  from  such  data  collected  at  a  mill  which  had  operated  some 
forty  years  with  a  water-wheel  equipment  representing  the  earliest  Ameri- 
can turbine  styles,  and  the  result  was  only  about  two  per  cent,  lower 
than  was  afterwards  found  from  measurements  and  gaugings  extending 
over  an  entire  year,  and  this  discrepancy  was  chargeable  to  leakage 
through  mill  tail-race. 

Where  weir  measurement  is  impracticable,  a  well-conditioned  cross 
section  of  the  stream  is  selected,  its  area  found  by  soundings,  and  the 
velocity  determined  with  which  water  passes  through  it  by  meters  or 
floats.  Part  II.,  Chapter  6,  treats  the  technical  phases  of  these  measure- 
ments and  of  the  instruments,  methods,  reductions,  and  computations; 
the  practical  application  for  preliminary  investigations  is  as  follows. 

Select  a  section  about  one  hundred  feet  long  on  a  straight  stretch, 
with  shores  parallel  and  of  gentle  and  even  slope,  containing  no  islands, 
visible  rocks,  or  other  obstructions,  and  where  the  water  appears  to  pass 
at  a  nearly  uniform  speed  throughout  the  entire  width.  Stretch  two 


.0 
0 


o 

u. 

13 

12 

11 

10 

9 

8 

7 

6 

5 


2.0    2.5     3.0    3.5 


, 


26 
25 
24 
23 
22 
21 
20 
19 
18 
17 
16 
15 
14 
13 
12 


Diagram  2 


Discharge    over 

flat- crested  Spillway 


H.E.P.2. 
H.V.S. 


0-5 


1.0          1.5 


2.0 


Overflow,    in    feet 


39 


40  HYDRO-ELECTRIC   PRACTICE 

lines  (|-inch  rope)  across  the  river,  secured  at  shore  and  one  hundred 
feet  apart.  Stretch  a  third  line  midway  between  these  two  and  mark  it 
off  in  ten-feet  sections  by  tying  on  it  alternately  red  and  white  bits  of 
cotton  ribbon.  When  the  river  is  wider  than  one  hundred  feet,  attach 
two  guy  lines  to  this  centre  line  so  that  a  boat  may  pass  along  without 
sagging  it  greatly  out  of  straight  line.  Find  the  depth  of  water  at  each 
red  and  white  marker  along  the  centre  line  by  differential  level  between 
water  surface  and  river  bed,  by  means  of  a  levelling  instrument  reading 
on  a  rod  held  by  a  man,  in  boat,  on  river  bottom.  Collect  chips  of  wood 
or  pieces  of  lath  or  bark  which  can  be  recognized  while  floating,  and 
have  man  in  boat  throw  one  at  a  time  in  the  river  some  fifty  feet  above 
the  upstream  line,  time  the  passage  of  float  under  upper  and  lower  lines, 
also  spot  the  red  or  white  marker  under  which  it  passes;  use  as  many 
floats  as  there  are  markers  in  the  line,  endeavoring  to  have  at  least  one 
pass  under  each.  Find  the  mean  of  the  velocities  observed,  the  product 
of  0.85  of  this  mean  velocity  and  the  cross  section  area  represents  the 
approximate  discharge  at  that  period  for  the  purpose  of  preliminary 
investigation.  Part  II.,  Chapter  6,  will  deal  with  and  describe  measure- 
ments by  meter,  surface  and  rod  floats,  and  of  reductions,  coefficients,  etc. 

ARTICLE  17.  —  The  fall  available  for  development  must  be  found 
from  the  total  fall  existing  in  entire  reach  of  stream  to  be  controlled, 
that  is,  from  the  upper  to  the  lower  point  to  be  affected  by  the  develop- 
ment, less  the  fall  represented  by  the  slope  in  the  upper  pool,  which  may 
be  from  0.05  to  0.5  feet  per  mile.  The  condition  of  river  stage  on  which 
these  fall  determinations  are  based  must  be  that  which  represents  the 
flow  to  be  utilized.  If  the  consideration  of  backswell  is  neglected,  the 
upper  pool  will  extend  beyond  the  expected  limit,  lands  will  be  flooded 
which  perhaps  have  not  been  secured,  and,  if  there  is  an  upper  develop- 
ment or  power  site,  the  upper  pool  water  will  trespass  on  its  tail  waters. 

When  available  fall  is  thus  fixed,  it  remains  to  be  determined  whether 
all  or  only  part  of  it  is  to  be  utilized,  which  will  depend  upon  the  topo- 
graphical conditions  as  influencing  location  and  character  of  develop- 
ment. The  constancy  of  the  fall  as  depending  upon  flow  fluctuations 
must  be  carefully  studied;  on  many  streams  the  fall  may  all  disappear 
during  extreme  floods. 

ARTICLE  18.  Power  Output. — The  unit  of  output  of  a  hydro-electric 
development  is  the  electrical  horse-power,  being  representative  of  the 
power  available  for  actual  work. 


POWER   OPPORTUNITY  41 

The  original  energy  is  hydraulic  power,  which  is  converted  by  means 
of  turbines  into  mechanical  power,  and  this  in  turn  into  electric  power; 
both  of  these  transitions  entail  some  loss  of  originally  available  energy, 
due  to  friction  in  one  form  or  another.  The  amount  of  this  loss  from 
hydraulic  to  electric  energy  depends  upon  the  type  of  the  machines  and 
their  mode  of  operation,  and  in  practice  is  generally  considerably  in 
excess  of  that  which  is  claimed  for  them  or  even  shown  by  tests.  After 
the  plant  is  in  operation  for  a  period,  it  is  found  that  efficiencies  of  76 
per  cent,  for  turbines  and  of  94  per  cent,  for  generators  may  be  obtained 
with  proper  equipment  correctly  installed.  Based  upon  these  the  electric 
power  realized  is  72  per  cent,  of  the  hydraulic  energy,  or  about  12^  cubic 
second  feet  with  one  foot  fall  represent  one  electric  horse-power. 

By  the  aid  of  Diagram  3  flow  and  fall  may  be  readily  converted 
into  electric  horse-power,  or  the  flow  required  for  certain  output  with 
fixed  fall  determined. 

Example.— Flow  250  c.  sec.  ft.,  fall  22  ft.  Output  =  440  E.H.P.  Fall 
30  ft.,  desired  output  100  H.P.,  required  flow  =  417  c.  sec.  ft. 

Having  found,  by  one  method  or  the  other,  the  monthly  mean  flow 
during  a  dry  year,  the  volume  on  which  maximum  development  may 
be  based,  which  will  be  called  the  power-flotv,  is  to  be  fixed  upon. 

The  development  plant,  with  exception  of  equipment,  will  gener- 
ally cost  nearly  as  much  for  a  small  as  for  a  large  output  development, 
and,  if  for  no  other  reasons,  this  is  sufficiently  important  to  seek  the 
development  into  useful  energy  of  the  greatest  possible  portion  of  the 
entire  flow  during  the  dry  year:  the  most  complete  utilization  of  this  is 
the  best  development.  However,  the  low  month  flow  presents  undis- 
putably  the  maximum  continuous  volume  which  is  available  for  twelve 
months;  if  any  higher  is  taken,  the  deficiency  must  be  made  up,  and  the 
substance  of  the  inquiry  lies  in  the  question,  "How  much  can  be  added 
to  the  low  flow,  and  from  what  source?" 

The  source  is  threefold:  the  market  conditions  may,  and  most 
generally  do,  call  for  current  service  only  during  a  portion  of  the  24 
hours;  in  that  case  the  plant  closes  at  the  expiration  of  the  operating 
period,  and  the  natural  flow  may  be  accumulated  by  pondage  above  the 
dam  during  the  remaining  portion  of  the  24  hours,  the  non-operating 
period.  This  is  accomplished  by  temporarily  raising  the  height  of  the 
pond  a  foot  or  more  through  the  fixing  of  flashboards  along  the  crest; 
the  ponded  flow  then  becomes  available,  together  with  the  natural  flow, 


42  HYDRO-ELECTRIC    PRACTICE 

during  the  succeeding  operating  period;  the  addition  will  not  be  large, 
but  every  12^  cubic  second  feet  represents  one  electrical  horse-power  for 
each  foot  fall.  For  instance,  the  low-month  flow  is  250  sec.  ft.,  the  fall 
30  feet,  the  non-operating  period  is  six  hours,  from  midnight  until  6 
A.M.;  the  accumulated,  or  ponded,  flow  will  be  250X21,600  =  5,400,000 
cub.  ft.,  and,  deducting  10  per  cent,  for  leakage  and  seepage,  the  quantity 
added  during  the  operating  period  of  18  hours  is  4,860,000-^64,800  = 
75  sec.  ft.,  which  represents  an  added  power  output  of  75^12.5x30 
=  180  horse-power;  the  low-month  flow  is  increased  to  325  sec.  ft.  If 
the  pond  is  two  miles  long  and  200  feet  wide  its  area  is  10,560X200  = 
2,112,000  sq.  feet,  and  the  dam  crest,  or  pond  level,  must  be  raised  by 
5,400,000^-2,112,000  =  2.5  feet. 

The  second  source  of  increasing  the  low  monthly  flow  is  from  storage. 
Some  of  the  stream's  tributaries  emptying  within  a  few  miles  above  the 
power  plant  may  present  suitable  reservoir  sites,  where  the  valley  can  be 
closed  by  an  economical  dam  structure  rising  to  a  moderate  height  of 
10  to  15  feet,  thereby  empounding  a  storage  reservoir;  such  a  dam  would 
be  of  the  earth  and  rock  fill  type,  with  a  suitable  timber  waste  gate,  as 
water  is  not  to  spill  over  the  structure.  The  reservoir  is  permitted  to 
fill  during  high-flow  season,  when  the  withdrawal  of  this  portion  from 
the  main  stream  is  of  no  consequence,  and  the  supply  is  drawn  out  dur- 
ing the  low  month  as  needed.  Taking  the  last  example  and  a  reser- 
voir site  of  250  acres  of  an  average  depth  of  ten  feet,  the  volume  stored 
is  250X43,560X10  =  108,900,000  cubic  feet,  the  daily  loss  from  evapora- 
tion and  seepage  of  about  2.5  per  cent,  will  be  replenished  by  the  nor- 
mal run-off  from  a  drainage  area  tributary  to  the  reservoir  site  of  about 
100  square  miles.  This  stored  volume  represents  an  18-hour  flow  for 
thirty  days  of  about  40  cub.  sec.  ft.  and  with  30  feet  fall  an  output  of 
96  horse-power.  Diagram  4  gives  continuous  flow  for  stated  periods 
from  a  water  surface  of  10  acres  area  and  one  foot  deep. 

Pondage  and  storage  may  be  combined,  and  in  the  case  cited  the  low 
flow  would  be  increased  from  250  to  365  sec.  ft. 

The  third  source  of  replenishing  the  low-month  output  is  by  auxiliary 
power.  When  the  hydro-electric  plant  goes  into  business,  some  power 
customers  may  be  found  who  are  then  using  steam  power,  and  arrange- 
ments can  be  made  with  them  by  which  the  use  of  their  steam-power 
plant  may  be  had  during  low-flow  seasons,  and,  in  that  event,  the  low- 
flow  output  can  be  increased  by  the  capacity  of  such  an  auxiliary  plant. 


POWER   OPPORTUNITY 


43 


130 
120 
110 
100 
90 
80 
70 
60 
50 
40 

*2 

«M 

30 

0 

I 

20 
A 

u 

10 

o 

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123456789 

130 
120 
110 
100 
90 
80 
70 
60 
50 
40 
30 
20 
10 

/ 

/ 

/ 

f 

/ 

/ 

Diagram  3 

Water    Power    and 
Electric    Power 

Efficiency    72    pet. 

/ 

7 

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44  HYDRO-ELECTRIC   PRACTICE 

The  entire  subject  of  developing  the  opportunity  in  excess  of  the 
low  dry-year  flow  is  one  of  comparisons  between  cost  of  reservoir  storage, 
or  auxiliary  plant,  or  both,  and  the  returns  from  additional  output  thus 
secured;  but  in  this  connection  it  must  be  borne  in  mind  that  increasing 
the  low-months  output  enables  the  plant  to  contract  for  delivery  of  this 
increase  during  the  entire  year,  while  the  auxiliary  plant  will  only  be 
operated  during  one  month. 

Given  the  reservoir  project  above  of  250  acres,  the  land  costing 
$25.00  an  acre  and  the  reservoir  dam  $2500.00,  the  increased  hydraulic 
and  electric  equipment  for  96  horse-power  $1500.00,  and  the  annual 
operating  cost  of  reservoir  gates  $250.00,  the  annual  charges  will  be 

Interest  6  per  cent,  on  investment  of  $10,250.00 $615 

Operation  of  reservoir 250  • 

Taxes  on  reservoir  site 200 

Maintenance  of  reservoir  dam 50     $1,115 

The  revenue  from  96  H.P.,  18  hr.,  at  $35.00  p.  year 3,360 

Annual  surplus $2,245 

From  which  may  be  deducted  for  sinking  fund 500 

Leaving  net  surplus  of $1,745 

This  amount  will  go  far  toward  meeting  the  operating  cost  of  the  gener- 
ating plant,  and  the  reservoir  is  therefore  a  profitable  addition. 

In  the  case  of  the  steam  auxiliary  of,  say,  100  horse-power  capacity, 
it  has  been  pointed  out  that  it  may  not  be  necessary  to  purchase  the 
plant,  as  arrangements  can  generally  be  made  to  use  an  existing  one; 
but,  supposing  the  plant  is  bought  outright  and  installed  at  the  hydro- 
electric station  so  that  one  of  the  generators  can  be  belted  to  the  engine, 
the  annual  accounts  would  be  like  this: 

Charges:  100  H.P.  steam  plant $6,000 

Housing 500 

Investment . .  . .  : $6,500 

Interest,  6  per  cent $390 

Fuel  at  3  pounds  per  H.P.  hours  for  18  hours  per  month,  81  tons,  @  $3 243 

Oil  and  waste 25 

Maintenance 125 

Taxes 132       $915 

(The  station  personnel  operates  the  plant.) 

Revenue  from  100  H.P.  at  $35 $3,500 

Surplus $2,585 

Charging  off  for  sinking  fund 325 

Net  surplus $2,260 


20 

15 

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Continuous  Flow 
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45 


46  HYDRO-ELECTRIC   PRACTICE 

The  low-flow  opportunity  represented  by  250  second  feet  and  30 
feet  fall  showed  an  output  of  600  horse-power;  by  pondage,  storage, 
and  auxiliary  power  this  has  been  increased  to  976  horse-power,  repre- 
senting a  flow  of  406  second  feet  at  a  net  gain  of  $4000.00  per  year. 

In  this  manner  the  entire  problem  of  what  the  development  scope 
should  be  is  to  be  argued  out  from  month  to  month  until  the  inevitable 
limit  is  reached.  In  fact,  hydro-electric  projects  are  rarely  developed  to 
their  most  resourceful  scope  at  the  beginning. 

The  immediate  demand  for  the  product,  it  is  true,  may  be  foretold 
with  considerable  accuracy,  but  this  will  grow ;  first  customers  gradually 
increase  their  demands  and  new  patrons  are  added,  as  the  advent  of  eco- 
nomical power  sooner  or  later  attracts  new  industries  to  a  community. 
The  development  scope  can,  therefore,  not  be  completely  exhausted 
when  the  project  is  investigated  and  planned;  but  so  much  of  it  as  will 
influence  the  required  investment  should  be  covered,  and  this  relates 
specifically  to  reservoir  storage  and  auxiliary  power  equipment;  other 
additions— as,  for  instance,  electric  storage — may  prove  recommendable 
after  the  plant  has  been  in  operation  some  time  and  the  market  condi- 
tions are  more  fully  developed. 


CHAPTER  III 

FEASIBILITY    AND    PRACTICABILITY 

The  feasibility  and  practicability  of  a  project  are  not  entirely  estab- 
lished because  the  power  and  market  are  available :  questions  of  Govern- 
ment control  on  the  stream,  of  State  laws  regulating  the  use  of  water, 
of  riparian  rights  and  land  titles  must  be  investigated  and  settled,  while 
the  practicability  of  economical  development  should  be  established. 

ARTICLE  19. — The  United  States  Government  exercises  constitutional 
control  over  all  navigable  waters,  and  the  question  as  to  the  navigability 
of  a  watercourse  rests  with  the  Congress.  When  provisions  are  made  by 
Congressional  legislation  to  examine  a  river  for  the  purpose  of  determin- 
ing whether  the  commercial  interests  and  the  physical  conditions  warrant 
navigation  improvements,  the  stream  passes  under  the  control  of  the 
War  Department,  and  no  works  of  any  description  for  the  development 
of  power  along  that  river,  or  so  much  of  it  as  is  covered  by  the  act,  can 
be  erected  without  the  consent  of  the  Secretary  of  War,  nor  can  such 
works  be  erected  on  rivers  where  navigation  improvements  have  been 
made  by  the  Government  without  a  like  consent.  The  policy  of  the  War 
Department  is  to  grant  such  permits  where  no  interference  with  navi- 
gation works  is  threatened,  reserving,  however,  a  revocable  authority. 
The  following  is  of  the  usual  tenor  of  such  grants. 

AN  ACT  permitting  the  building  of  a  dam  across  the  Red  Lake  River  at  or  near  the  junction  of  Black 
River  with  said  Red  Lake  River,  in  Red  Lake  County,  Minnesota. 

BE  IT  ENACTED,  by  the  Senate  and  House  of  Representatives  of  the  United  States  of  America  in 
Congress  assembled,  That  the  consent  of  Congress  is  hereby  granted  to  William  J.  Murphy,  his  suc- 
cessors and  assigns,  to  build  a  dam  across  the  Red  Lake  River  at  or  near  the  junction  of  the  Black 
River,  so  called,  with  said  Red  Lake  River,  in  Red  Lake  County,  Minnesota,  for  the  development  of 
water-power,  and  such  works  and  structures  in  connection  therewith  as  may  be  necessary  or  convenient 
in  the  development  of  said  power  and  in  the  utilization  of  the  power  thereby  developed:  Provided, 
That  the  plans  for  the  construction  of  said  dam  and  appurtenant  works  shall  be  submitted  to  and 
approved  by  the  Chief  of  Engineers  and  the  Secretary  of  War  before  the  commencement  of  the  con- 
struction of  the  same:  And  provided  further,  That  the  said  William  J.  Murphy,  his  successors  or  assigns, 
shall  not  deviate  from  such  plans  after  such  approval,  either  before  or  after  the  completion  of  said 
structures,  unless  the  modification  of  said  plans  shall  have  previously  been  submitted  to  and  received 
the  approval  of  the  Chief  of  Engineers  and  of  the  Secretary  of  War:  And  provided  further,  That  there 
shall  be  placed  and  maintained  in  connection  with  said  dam  a  sluice-way,  so  arranged  as  to  permit 
logs,  timber,  and  lumber  to  pass  around,  through,  or  over  said  dam  without  unreasonable  delay  or 
hinderance  and  without  toll  or  charges:  And  provided  further,  That  the  dam  shall  be  so  constructed 

47 


48  HYDRO-ELECTRIC   PRACTICE 

that  the  Government  of  the  United  States  may  at  any  time  construct  in  connection  therewith  a  suitable 
lock  for  navigation  purposes,  and  may  at  any  time,  without  compensation,  control  the  said  dam  so  far 
as  shall  be  necessary  for  purposes  of  navigation,  but  shall  not  destroy  the  water-power  developed  by 
said  dam  and  structures  to  any  greater  extent  than  may  be  necessary  to  provide  proper  facilities  for 
navigation,  and  that  the  Secretary  of  War  may  at  any  time  require  and  enforce  at  the  expense  of  the 
owners  such  modifications  and  changes  in  the  construction  of  such  dam  as  he  may  deem  advisable  in 
the  interests  of  navigation:  And  provided  further,  That  suitable  fishways,  to  be  approved  by  the  United 
States  Fish  Commission,  shall  be  constructed  and  maintained  at  said  dam  by  the  said  William  J.  Murphy, 
his  successors  or  assigns. 

SEC.  2.  That  in  case  any  litigation  arises  from  the  building  of  said  dam,  or  from  the  obstruction 
of  said  river  by  said  dam  or  appurtenant  works,  cases  may  be  tried  in  the  proper  courts,  as  now  pro- 
vided for  that  purpose  in  the  State  of  Minnesota  and  in  the  courts  of  the  United  States:  Provided, 
That  nothing  in  this  Act  shall  be  so  construed  as  to  repeal  or  modify  any  of  the  provisions  of  law  now 
existing  in  reference  to  the  protection  of  the  navigation  of  rivers,  or  to  exempt  said  structures  from  the 
operation  of  same. 

SEC.  3.  That  this  Act  shall  be  null  and  void  unless  the  dam  herein  authorized  be  commenced 
within  one  year  and  be  complctoJ  within  three  years  from  the  time  of  the  passage  of  this  Act. 

SEC.  4.     That  the  right  to  amend  or  repeal  this  act  is  hereby  expressly  reserved. 

Approved,  March  16,  1906. 

LEASE  EXECUTED  BY  WAR  DEPARTMENT. 

WHEREAS,  By  an  Act  of  Congress,  approved  September  19,  1890,  entitled  "An  Act  making 
appropriations  for  the  construction,  repair,  and  preservation  of  certain  public  works  on  rivers  and 
harbors,  and  for  other  purposes,"  it  is  provided  that  the  Secretary  of  War  is  authorized  and  empowered 
to  grant  leases  or  licenses  for  the  use  of  water-powers  on  the  Green  and  Barren  Rivers,  at  such  a  rate 
and  on  such  conditions  and  for  such  periods  of  time  as  may  seem  to  him  just,  equitable,  and  expedient; 
said  leases  not  to  exceed  the  period  of  twenty  years;  Provided,  That  the  leases  or  licenses  shall  be  limited 
to  the  use  of  the  surplus  water  not  required  for  navigation. 

AND  WHEREAS,  MR.  T.  LINDSEY  FITCH,  of  Louisville,  Kentucky,  has  applied  to  the  Secretary  of 
War  for  the  lease  of  the  surplus  water-power  at  Dam  No.  5,  Green  River,  Kentucky,  for  manufacturing 
purposes,  and  also  a  small  tract  of  land,  in  connection  therewith,  at  the  abutment  end  of  said  Dam 
No.  5,  the  leasing  of  which  said  water-power  and  land  has  been  recommended  by  the  Chief  of  Engineers, 
United  States  Army: 

Now,  THEREFORE;  I,  F.  C.  Ainsworth,  the  Military  Secretary,  Acting  Secretary  of  War,  under 
authority  of  the  Act  of  Congress  aforesaid,  and  in  consideration  of  the  rental  herein  provided  for,  and 
of  the  covenants  and  conditions  herein  to  be  kept  and  performed  by  the  lessee,  have  leased,  and  by 
these  presents  do  hereby  lease,  unto  the  said  T.  Lindsey  Fitch,  for  the  term  of  nineteen  (19)  years  and 
five  (5)  months  from  the  tenth  day  of  August,  1906,  the  surplus  water-power  at  Dam  No.  5,  Green 
River,  Kentucky,  for  manufacturing  purposes,  and,  in  connection  therewith,  the  following  described 
parcel  of  United  States  land  at  the  abutment  end  of  said  Dam  No.  5;  said  parcel  of  land  hereby  leased 
is  described  as  follows: 

Beginning  at  a  point  in  the  southerly  boundary  line  of  the  parcel  of  land  now  owned  by  the  United 
States  at  the  abutment  end  of  Dam  No.  5,  Green  River,  Kentucky;  said  point  being  80  feet  from  the 
southeast  corner  of  said  land;  thence  S.  71°  30'  W.  200  ft.,  thence  N.  18°  30'  W.  100  ft.,  thence  71° 
30'  E.  200  ft.,  and  thence  S.  18°  30'  E.  100  ft.,  to  the  place  of  beginning;  at  the  location  and  as  shown 
on  the  attached  blue-print. 

The  said  lessee  paying  therefor  the  sum  of  three  hundred  dollars  per  annum,  as  hereinafter  speci- 
fied, and  subject  to  the  following  provisions  and  conditions: 

1.  That  the  said  lessee  shall  bear  all  the  expense  of  providing  and  maintaining  suitable  and  sub- 
stantial means  of  conducting  the  water  to  and  from  the  wheel  or  wheels  used  for  power  purposes,  all 
of  which  means  shall  be  of  such  design  as  to  meet  the  approval  of  the  Engineer  Officer  of  the  United 
States  Army,  in  charge  of  Green  and  Barren  Rivers,  Kentucky;  such  approval  to  be  obtained  before 
any  original,  modifying,  or  renewal  construction  is  begun. 


FEASIBILITY  AND   PRACTICABILITY  49 

2.  That  the  location  of  the  structure  to  be  placed  upon  the  parcel  of  land  leased  shall  be  subject 
to  the  prior  approval  of  said  engineer  officer,  in  charge  of  said  rivers. 

3.  That  the  use  of  said  water  for  power  is  only  given  for  such  period  of  time  as  such  use  will  not 
interfere  with  the  navigation  of  the  stream  from  which  said  water  is  drawn;    and  the  United  States 
hereby  reserves  the  right  to  determine,  through  its  officers  and  agents,  when  the  use  of  water  for  power 
interferes  with  navigation;   the  said  lessee  to  abide  by  such  determination  whenever  made. 

4.  That  no  rebate  shall  be  allowed  to  said  lessee  for  periods  of  time  when  the  use  of  said  water 
for  power  is  not  permitted,  except  in  cases  of  stoppages,  under  such  conditions,  for  a  period  of  thirty 
(30)  consecutive  days,  or  more;  on  which  event  the  rebate  is  to  be  determined  by  multiplying  the 
annual  rental  by  a  fraction  in  which  the  denominator  will  be  three  hundred  and  sixty-five  (365)  and 
the  numerator  the  number  of  days  during  which,  as  above,  the  use  of  the  water  was  not  permitted  by 
the  United  States. 

5.  That  this  lease  is  only  for  the  use  of  the  land  hereinbefore  described  and  the  use  of  said  surplus 
water  for  power;  and  shall  not  be  transferred  or  assigned,  except  by  the  consent  of  the  Secretary  of  War. 

6.  That  said  lessee  shall  pay  for  the  use  of  the  said  ground  and  water  an  annual  rental  of  $300.00, 
and  shall  place  and  maintain  such  electric-light  fixtures  and  conductors  as  said  Engineer  Officer  may 
desire  to  have  placed  on  the  Lock  Walls  and  in  the  cottages  and  office  at  Lock  No.  5,  Green  River, 
and  shall  furnish  necessary  electric  current  to  light  the  said  buildings  and  structures,  all  free  of  cost  to 
the  United  States. 

7.  That  work  on  the  proposed  plant  for  the  utilization  of  said  water  shall  be  begun  within  one 
year  from  the  date  of  this  lease  and  shall  be  completed  without  unnecessary  delay. 

8.  That  no  rental  under  this  lease  shall  accrue  until  the  construction  of  the  proposed  plant  is 
begun;  then,  beginning  with  that  date,  there  shall  accrue  one  three  hundred  and  sixty-fifth  part  of  the 
annual  rental  for  each  day  until  the  following  January;   which  amount  shall  be  paid  on  or  before  Jan- 
uary 10th.    Succeeding  payments  of  the  annual  rental  shall  be  made  not  later  than  January  10th,  each 
year,  during  the  life  of  this  lease. 

WITNESS  my  hand  and  official  seal,  this  last  day  of  August,  1906. 

(Signed)  F.  C.  AINSWORTH, 
The  Military  Sec'y,  Acting  Sec'y  of  War. 

THIS  INSTRUMENT  is  also  executed  by  T.  Lindsey  Fitch,  in  testimony  of  the  acceptance  by  him 
of  the  provisions  of  the  Act  of  Congress  aforesaid  and  the  provisions  and  conditions  herein  imposed. 
WITNESS  my  hand  and  seal,  this  6th  day  of  -August,  1906. 

(Signed)  T.  LINDSEY  FITCH. 
(Signed)  J.  M.  MARTIN,  JR. 
(Signed)  JAMES  F.  HUTTY. 

REVOCABLE  LICENSE  ISSUED  BY  WAR  DEPARTMENT. 

The  Edison  Sault  Light  and  Power  Company  of  Sault  Ste.  Marie,  a  corporation  existing  under 
the  laws  of  the  State  of  Michigan,  is  hereby  granted  a  license,  revocable  at  will  by  the  Secretary  of 
War,  to  erect  and  maintain  a  dam  on  the  Rapids  of  the  St.  Mary's  River  between  the  mainland  and 
Island  No.  3,  and  within  the  limits  of  the  lines  marked  "Proposed  Embankment  Dam"  on  the  map 
hereto  attached  and  made  a  part  of  this  instrument,  upon  the  following  provisions  and  conditions: 

1 .  That  said  dam  shall  be  so  constructed  as  not  to  interfere  with  private  rights  or  public  interests 
and  improvements. 

2.  That  the  enigneer  officer  of  the  United  States  Army,  in  charge  of  the  district  within  which 
the  dam  is  to  be  constructed,  may  supervise  its  construction  so  far  as  may  be  necessary  to  secure  the 
compliance  with  the  conditions  herein  contained. 

3.  That  any  sum  which  may  have  to  be  expended,  after  revocation  of  this  license,  in  putting  any 
premises  or  property,  hereby  authorized  to  be  occupied  or  used,  in  as  good  condition  for  use  by  the  United 
States  as  it  is  at  this  date  shall  be  repaid  by  said  Edison  Sault  Light  and  Power  Company  on  demand. 

Witness  my  hand,  this  fourteenth  day  of  March,  1889. 

REDFIELD  PROCTOR, 

Secretary  of  War. 
4 


50  HYDRO-ELECTRIC    PRACTICE 

TABLE  3.— WATERCOURSES  IN  THE  UNITED  STATES  UNDER  CONTROL  OF  THE 

WAR  DEPARTMENT. 

Navi- 
River.  State,  gable.  From  Since  To  be  extended.  New  Project. 

Alabama Ala Yes.  .  Wetumpka 1878 

Allegheny Pa Yes 1879 

Altamaha Ga Yes . . 

Appomattox Va Yes.  .Petersburg 1902 

Arkansas Kans Yes.  .Muskogee,  I.  T 1886 

Au  Sable Yes Project 

Bad Mich Yes.  .St.  Charles 1902 

Barren Ky Yes . .  Bowling  Green 1879 

Beech Tenn Project 

Belle Mich Yes 1896 

Bennetts N.  C Gatesville Project 

Big  Sandy Ky Yes.  .Louisa 1880 

Big  Sandy Tenn Big  Sandy Project 

Big  Sandy Va Project 

Big  Sunflower. .  .Miss Project 

Black Ark.  and  Mo. .  Yes 1880 

Black Mich Yes 1872 

Black N.  C Yes.  .Lisbon 1885 

•DI     i   -nr      •  T7          [  Mulberry,  1902 

Black  Warrior  . .  Ala Yes. .  i  ,  ;,'  , 

I  Locust  Forks 

Bois  de  Sioux. . .  Minn Project 

Brazos Tex Yes.  .Waco 1902 

Broad S.  C 99  Ind.  Shoal 

Cache Ark Yes.  . Riverside 1888 

Caney  Fork Tenn Yes 1906 

Cape  Fear N.  C Yes. . Fayetteville 1902 

Chattahoochee  . .  Ga.  and  Ala . . .  Yes . .  Columbus 1874 

Cheat W.  Va ". 25  miles  from  mouth 

Chester Md Yes.  .Jones  Ldg 1890 

Choctawhatchee.Fla.  and  Ala.  .Yes.  .Geneva 1874 Newton 

Clatskanie Ore Yes.  .Clatskanie 1898 

Clearwater Ida Yes .  .  North  and  South  Fork  1879 

Clinch Tenn Yes.  .Haynes 1880 

Clinton Mich Yes.  .2700  ft.  ab.  mouth. . .  1870 

Coan Va Project 

Cocheco N.  H Yes . .  Dover 1871 

Columbia Ore.,  Wash Yes.  .Lewiston,  Ida 1877 

Conecuh Ala Yes 1907 

Congaree S.  C Yes.  .Granby .1899 Broad  River 

Connecticut Conn Yes.  .Hartford 1870.  .Holyoke 

Contentnia N.  C Yes.  .Snow  Hill 1894 

Coos Ore Yes 1896 

Coosa Ga.  and  Ala. . .  Yes. . Wetumka 1890 Horseley  Shoal 

Coquille Ore Yes.  .Myrtle  Pt 1878 

Cowlitz Ore Yes 1880 

Cumberland Ky.  and  Tenn .  Yes . .  Burnside 

Current Ark.  and  Mo . .  Yes 1872 

Damariscotta  . .  .  Me Yes .  . 

Delaware Pa.,  N.  J.,  Del .  Yes .  .  Philadelphia Bordentown 


FEASIBILITY   AND   PRACTICABILITY  51 

Navi- 
River.  State.  gable.  From  Since  To  be  extended.  New  Project. 

Duck Tenn Centerville 

Edisto,  N.  Fork  .  S.  C Orangeburg 

Edisto,  S.  Fork.  .S.  C Scotts  Bridge 

Elk Tenn Fayetteville 

Elk W.  Va Yes 1878 

Escambia Fla Yes.  .Ala.  State  line 1880 

Exeter N.  H Yes.  .Exeter 1899 

Flathead Mont Yes 1896 

Flint Ga Yes.  .Albany 1874 

Flint Mich Yes 1902 

Forked  Deer  . . .  .Tenn Yes 1896 

Fox Ill Yes 

Fox Wis Yes 1872 

French  Broad. .  .Tenn Yes 1880 

Galena Ill Yes 1884 

Ganley W.  Va Yes.  .28  miles  ab.  Roughs.  .  1888 

Gasconade Mo Yes 1880 Gasconade 

Georges Me Yes 1896 

Grand Mich Yes 1866 

Grays Wash Yes 

Great  Pedee S.  C Yes.  .Georgetown 1902 Dee  Station 

Green Ky Yes 1891 .  .  Minforclsville 

Guyandot. W.  Va Yes 1878 

Hatchie Tenn Brownville 

Hiawassee Tenn Yes .  .  Oeoce  River 1877 

Holston Va.  and  Tenn. Yes 1902 

Housatonic Conn Yes.  .Stratford 1871 

Hudson N   Y Yes .  .  Waterford 

Illinois Ill Yes 1852 

Ipswich Mass 

James Va Yes.  .Richmond 1870 

Kalamazoo Mich Yes 1868 

Kanawha W.  Va Yes 

Kennebec Me Yes.  . Gardiner 1866 

Kennebuck Me Yes 

Kentucky Ky Yes 1879 

Kootenai Ida Yes.  .Int.  Boundary 1896 

Leaf Miss Yes.  .Bowie  Creek 1890 

Lewis Ore Yes .  .  Lacenter 1897 

Little  Kanawha. W.  Va Yes 1876 

Little  Pigeon. . .  .Tenn Yes 1892 

Long  Tom Ore Yes 1898 

Maiden Mass Yes 1882 

Mattaponi Va. .  .  .- Yes.  .  Aylett 1880 

Maumee Ohio Yes .  .  Toledo 

Meherrin N.  C Yes.  . Murf reesboro 1907 

Menominee Wis.,  Mich.  .  .  .Yes 1890 

Merrimac Mass Yes * 1870 Haverhill 

Minnesota Minn Yes .  .  Yellow  Medicine  Riv.  .  1867 

Mississippi Minn Yes.  .Grand  Rapids 1902 

Missouri Sioux  City 


52  HYDRO-ELECTRIC   PRACTICE 

Navi- 
River.  State.  gable.  From  Since  To  be  extended.  New  Project. 

Monongahela Pa.  and  W.  Va.  Yes 1897 

Muskingum Ohio Yes .  .  Zanesville 1888 

Mystic Mass Yes 1880.  .Somerville 

Napa Cal Yes 1888 

Narragnagus. . .  .Me Yes 1871 .  .Yes 

Neuse N.  C Yes.  .Goldsboro 1871 

New N.  C Yes 1882 Jacksonville 

Obion Term Yes 1892 

Ocmulgee Ga Yes.  .Macon 1876.  .  Joliet 

Oconee Ga Yes .  .  Milledgeville 1891 .  .  Oconee  Sta. 

Ohio Ohio Yes 1825.  .Metropolis,  111. 

Okanogan Wash Yes 1899 

Osage Mo Yes 1871 Niangua  River 

Otter Vt Yes.  .  Vergennes 1872 

Pamlico N.  C Yes.  .Little  Fall 1889.  .Greenville 

Pamunkey Va Yes.  . Hanovertown 1880 

Patuxent Md Yes.  .Bristol 1902 

Pawcatuck R.  I Yes 

Pearl Miss Yes.  .Jackson 1879.  .Rockport 

Penobscot Me Yes .  .  Bangor 1870 

Pine Mich Yes 1896 

Pomoke Md. , Yes 1878 

Potomac Va Yes.  .Washington 

Powow Mass Yes 1885 

Providence R.  I Yes 1852 

Rainy Minn Project 

Rappahannock .  .  Va Yes.  . Fredericksburg 1871 

Raritan N.  J Yes.  .New  Brunswick 1878 

Red Ark.  and  Tex  .Yes.  . Fulton,  Ark 1907 

Red  of  the  North  Minn.,  N.  Dak.  Yes.  .  Goose  Rapids 1877     Int.  Bound. 

Richland Tenn Project 

Roanoke N.  C Yes.  . Weldon 1902 

Rock Ill Yes 1890 

Rogue Mich Yes 1906 

Rouge Mich Yes 1888 

Rough Ky Yes 1890 

Saco Me Yes 1827 

Sacramento Cal Yes.  .Sacramento 1899 

Saginaw Mich Yes 1866 

Saint  Croix Wis.,  Minn Yes.  .Taylor's  Falls 1875 

Saint  Francis  . .  .Ark.  and  Mo  .  .Yes.  .Kennett 1884 

Saint  Johns Fla Yes.  .Jacksonville 1896 

Saint  Joseph.  .  .  .Mich Yes 1836 

Saint  Lawrence  .  N.  Y Yes 

Saint  Mary's ....  Mich Yes 

Sakonnet R.  I Yes 1896 

Saline Ark Turtle  Bar 

Saluda S.  C Hollow  Creek 

San  Joaquin  . . .  .Cal Yes.  .Stockton 1877 

Santee S.  C Yes ..  Mosquito  Cr .1881 

Sasanoa Me Yes 


FEASIBILITY   AND   PRACTICABILITY  53 

River.  State.  gable.  From  Since  To  be  extended.  New  Project. 

Savannah Ga Yes.  .Trotters  Shoal 1880 

Saugatuck Conn Yes 1827 

Saugus Mass Project 

Sebewiany Mich Yes 1875 

Shallotte N.  C Yes.  .Shallotte 1906 

Shem S.  C Project 

Shiawassee Mich Yes 1902 

Shipyard S.  C Project 

Simpsy Ala Fayette 

Snohomish Wash Yes.  .Stretch's  Riffle 

South N.  C Aurora 

Susquehanna. . .  . Md Yes.  . Havre  de  Grace 1852 

Tallahatchie  ....  Miss Yes Batesville 

Tar N.  C Yes.  .Tarboro 1894.  .Greenville 

Taunton Mass Yes 1870 

Tennessee Tenn Yes 1871 

Thames Conn Yes.  .Allyn's  Pt 1886 

Thunder  Bay  . .  .  Mich Yes Batesville 

Tombigbee Ala Yes.  .Columbus,  Miss 1888 

Town Mass Yes 1896 

Trent N.  C Yes.  . Newbern 1879 Trenton 

Trinity Tex Yes.  .Dallas 1902 

Union Me Yes 1873.  .Yes 

Wabash Ind.  and  111  . . .  Yes.  .Grand  Rapids 1872 

Waccamaw N.  and  S.  C.  .  .Yes.  .Lake  Waccamaw 1880 

Wateree S.  C Yes.  .Camden 1881 

Weymouth Mass Yes 1890 

White Ark Yes.  .  Buffalo  Shoals 1899 

White Ind Yes 1879 

White  Oak N.  C Maysville 

Wicomico Md Yes 1872 

Willamette Ore Yes.  .Eugene 1878 

York Va Yes 1860 

Youghiogheny  .  .  Pa • Connellsville 

ARTICLE  20. — On  navigable  rivers  the  title  to  shore  lands  carries  to 
low-water  line,  while  on  non-navigable  streams  it  goes  to  the  middle  of 
the  watercourse,  securing  to  the  owner  the  use  of  the  water  within  the 
boundaries  of  his  lands  for  floatage,  power  purposes,  and  fisheries,  but 
no  portion  of  the  volume  can  be  diverted  from  its  normal  course  or  put 
to  such  a  use  that  the  natural  flow  or  fall  pertaining  to  any  land  not 
owned  by  him  is  thereby  periodically  or  permanently  diminished  or 
changed.  The  State  retains  control  of  the  land  under  the  water,  and  several 
have  enacted  laws  reserving  the  approval  of  any  permanent  structures 
such  as  are  required  for  power  development;  this  right,  however,  does 
not  include  the  power  of  prohibition  of  such  works,  but  merely  of  securing 
safety  of  structures  and  of  provisions  guaranteeing  non-interference  with 


54  HYDRO-ELECTRIC   PRACTICE 

the  floatage  of  timber  and  the  passage  of  fish  to  their  accustomed  breed- 
ing-grounds. Some  of  the  States  have  constructed  navigation  canals 
along  certain  rivers,  and  in  this  connection  have  reserved  control  of  a 
portion  of  the  flow  and  of  certain  reservoirs  maintained  for  the  feeding 
of  the  canal  system;  water-power  development  on  such  streams  must 
conform  to  statutes  enacted  for  the  protection  and  maintenance  of  such 
State  canals.  The  Western  States  have  legislated  on  the  use  of  water 
of  streams  for  the  purpose  of  guaranteeing  its  equitable  distribution  to 
adjacent  land  for  irrigation,  and  in  these  the  permit  of  the  respective 
authorities  must  be  secured  for  the  use  of  any  volume  for  power  purposes ; 
and,  finally,  the  Federal  Government  has  taken  possession  of  certain 
streams  in  the  arid  regions  for  purposes  of  national  irrigation  projects, 
and  from  these  all  other  utilization  of  their  waters  is  excluded. 

The  legal  requirements  and  limitations  relating  to  water-power 
development  expressed  in  Federal  and  State  statutes  in  the  United 
States,  Canada,  and  Mexico  are  now  being  compiled  by  the  author,  and 
will  be  published  in  the  near  future. 

ARTICLE  21. — The  practicability  of  an  economical  development  is  solved 
only  after  the  programme  has  been  fixed  upon,  the  plant  designed,  and 
estimates  made,  all  of  which  is  treated  in  detail  in  Part  II.;  in  some 
cases,  however,  difficulties  to  be  met  may  be  so  apparent  and  the  great 
expense  of  overcoming  them  so  patent  that  the  undertaking  may  be 
pronounced  prohibitive  without  the  necessity  of  detail  engineering  studies. 
Market  and  power  capacity  enter  into  this  problem,  and  in  fact  their 
proper  consideration  will  frequently  terminate  the  entire  inquiry.  Many 
excellent  water-power  opportunities  are  undeveloped  to-day  and  will 
remain  so  for  some  time  to  come,  because  there  is  no  market  available 
for  their  output,  nor  is  there  any  in  sight  for  many  years  to  come  unless 
electric  power  is  utilized  by  railroads  generally  for  their  passenger  busi- 
ness, which  is,  no  doubt,  among  the  probabilities  of  the  near  future.  In 
some  cases  even  the  best  available  development  site  reveals,  upon  pre- 
liminary examinations,  such  difficulties,  as  to  length  of  required  dam 
and  unstable  material  at  its  logical  location,  that  it  becomes  at  once 
evident  the  cost  of  the  necessary  works  will  be  out  of  all  proportion  to  the 
power  which  may  be  secured;  and,  finally,  the  constancy  of  the  output 
may  be  proved  to  be  entirely  void  of  any  reasonable  guarantee  of  that 
continuity  which  must  underlie  the  enterprise  which  proposes  to  meet 
binding  contract  obligations. 


FEASIBILITY   AND   PRACTICABILITY  55 

ARTICLE  22.  —  The  investment  balance,  or  the  summation  of  the 
capital  outlay  and  the  returns  promised  by  the  enterprise,  is  the  quintes- 
sence of  the  analysis  of  a  hydro-electric  project;  if  this,  being  based 
upon  authoritative  facts,  makes  a  satisfactory  showing,  and  the  develop- 
ment is  found  to  be  feasible,  its  realization  is  a  certainty. 

The  treatment  of  this  subject  is  the  same  as  that  of  any  other  com- 
mercial proposition :  charges  and  revenue  are  the  components.  The  first 
consist  of  interest  on  investment,  sinking  fund,  maintenance,  operation, 
depreciation,  taxes,  and  insurance;  the  second,  of  receipts  from  sale  of 
product.  An  annual  charge  of  8  per  cent,  on  capital  investment  will 
meet  the  interest  of  5  per  cent,  and  the  retiring  of  a  bond  issue  represent- 
ing the  investment  in  20  years.  Maintenance  and  depreciation  should 
be  charged  at  2  per  cent,  of  the  cost  of  the  works  and  3  per  cent,  of  that 
of  equipment;  operation  cost  of  generating,  transmission,  and  distribut- 
ing plant  may  be  estimated  on  a  personnel  of  two  shifts,  each  composed 
of  an  operator  and  assistant  and  of  one  lineman  for  day  service,  which 
is  required  for  a  plant  whether  of  500  or  5000  horse-power  output,  or  a 
line  5  or  25  miles  long;  the  wages  allowed  should  not  be  less  than  $90.00 
for  the  operators,  $60.00  for  assistants  and  $75.00  for  linemen.  The 
maintenance  charge  will  cover  oil,  waste,  wire,  insulators,  and  all  other 
needed  repair  material.  Taxes  are  generally  2  mills  on  a  f  valuation. 
Insurance  is  not  always  placed  on  hydro-electric  plants,  as  the  fire  risk 
is  small. 

Tabulating  these  charges  for  a  plant  of  1000  horse-power  with  ten- 
mile  transmission  line,  the  fixed  items  are  the  cost  of  the  generating 
equipment,  which  will  be  about  $20.00  per  horse-power,  cost  of  trans- 
mission equipment  (transformers)  $6.00  per  horse-power,  and  of  sub- 
station at  market  end  $2000.00;  no  estimate  is  made  for  distribution 
and  service  lines  and  equipment,  and  the  receipts  from  current  are 
assumed  to  be  its  wholesale  value  at  the  substation,  or  $30.00  per  horse- 
power-year. 

The  statement  for  one  horse-power  ratio  will  be 

Charges : 

Interest  on  sinking  fund $  4.28 

Maintenance  and  depreciation 1 .59 

Operation 8.22 

Taxes  and  insurance 0.80 

Income 30.00 

Balance .  15.11 


56  HYDRO-ELECTRIC   PRACTICE 

This  balance  must  meet  interest  and  sinking  fund  at  8  per  cent, 
and  maintenance  and  depreciation  at  2  per  cent,  of  the  cost  of  the  works, 
consisting  of  a  dam,  intake,  power-house,  and  tail-race,  of  lands,  right  of 
way,  taxes,  and  discount  from  face  value  of  securities  and  service  charges, 
and  represent  a  principal  of  about  $140.00  per  horse-power;  or,  in  other 
words,  the  cost  of  these,  the  works,  lands,  etc.,  must  not  exceed  $140.00 
per  horse-power  in  order  that  the  enterprise  may  meet  fixed  charges, 
while  a  smaller  cost  will  leave  a  corresponding  surplus.  If,  for  example, 
the  cost  of  items  not  above  included  aggregates  $70,000,  of  which  $50,- 
000  is  cost  of  works,  then  the  statement  is: 

Cost  of  complete  development $123,500.00 

Capital  investment 137,200.00 

Interest  and  sinking  fund  at  8  per  cent 11,000.00 

Maintenance  and  depreciation 2,590.00 

Operation 8,220.00 

Taxes  and  insurance 1,800.00 

Income 30,000.00 

Surplus 6,390.00 

or  about  5  per  cent,  on  the  investment. 

The  operating  charge  is  the  largest  item,  and,  since  this  does  not 
materially  increase  with  a  greater  output  up  to  about  5000  horse-power, 
the  larger  capacity  developments  will  show  a  greater  surplus. 

The  income  from  current  is  here  taken  rather  low,  being  for  ten-hour 
motor  service  at  a  rate  of  1.3  cents  per  kilowatt-hour,  and  for  eigh teen- 
hour  traction  service  only  about  0.6  of  a  cent,  both  of  which  are  con- 
siderably below  average  values;  however,  the  same  line  of  investigation 
adapts  itself  to  the  probable  value  of  the  output  as  found  from  market 
investigations,  and,  when  investment  required  is  known,  the  balance 
statement  can  be  safely  made  up  along  these  lines. 

Diagrams  5,  6,  and  7  show  the  fixed  charges  per  horse-power  for 
plants  of  varying  capacity  and  total  investment,  and  by  the  aid  of  Dia- 
gram 8  the  horse-power  per  year  values  can  readily  be  converted  into 
kilowatt-hour  rates  for  the  three  classes  of  current  service,  light,  motor, 
and  traction. 


FEASIBILITY   AND   PRACTICABILITY 


57 


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CHAPTER  IV 

COST   OF    DEVELOPMENT 

THE  COST  of  the  development  can  be  found  correctly  only  from 
estimates  based  upon  a  well-defined  programme  and  the  plans  and  detail 
designs  of  the  required  structures,  all  of  which  is  treated  exhaustively 
in  Part  II.  Only  some  general  rules  and  guides  are  given  here,  by  which 
an  approximate  first  estimate  of  such  cost  may  be  found. 

ARTICLE  23. — The  cost  of  the  dam,  only  the  spillway  proper  being 
here  considered,  depends  not  only  upon  the  type  to  be  built  but  also 
upon  the  conditions  of  flow  and  character  of  river  bed.  A  reasonable 
allowance  must  be  made  for  controlling  the  flow  during  construction 
period,  which  may  require  erection  of  coffer-dams  of  more  or  less  sub- 
stantial design  and  the  operation  of  a  pumping  plant.  Where  the  river 
is  shallow  and  the  possibilities  of  a  material  rise  during  construction 
period  are  remote,  this  item  may  not  be  very  important;  sheet  piling 
often  proves  sufficient  to  exclude  the  flow  from  the  area,  the  seepage 
being  accumulated  in  one  sump  and  thence  removed  by  moderate  pump- 
ing. Again  well-constructed  timber  cribs  loaded  with  rock  may  be 
required  to  guard  against  flooding  and  a  large  capacity  pumping  plant 
needed  to  perform  continuous  duty.  Sheet  piling,  where  gravel  and 
boulders  prevail,  is  best  of  interlocking  steel  material,  which  will  cost 
from  $1.50  to  $3.00  per  foot  length  of  piles  in  place,  depending  upon  the 
depth  to  which  they  are  to  be  driven.  In  rock  or  hard  bottoms  timber 
cribs  must  be  employed  to  coffer  the  desired  area;  these  are  constructed 
of  square  timber  suitably  framed,  from  6  to  10  feet  wide,  filled  with  rock 
and  puddling  material;  if  water  is  shallow,  rock  diking  with  puddling 
placed  on  outside  may  answer  the  purpose.  The  characteristics  of  the 
flow,  of  material  in  river  bed,  and  probable  duration  of  construction  under 
such  safeguards  must  decide  the  means  to  be  employed;  at  any  rate, 
the  item  "control  of  flow"  is  an  important  one,  and  may  be  from  a  few 
hundreds  to  several  thousands  of  dollars.  For  some  dam  constructions 
it  will  be  less  than  for  others,  even  on  the  same  site;  with  a  structure,  for 
instance,  consisting  of  piers  rather  than  a  continuous  mass  of  masonry 
the  completed  portion  can  readily  be  utilized  for  water-way  while  the 

61 


62  HYDRO-ELECTRIC   PRACTICE 

remaining  is  being  built;  like  methods  can  be  employed  with  concrete- 
steel  dams. 

This  brings  us  to  the  type  of  dam  itself,  which  should  be  chosen 
because  of  its  peculiar  fitness  to  the  conditions  and  purpose  as  well  as 
for  considerations  of  first  cost.  Part  II.  treats  this  point  in  all  its  prac- 
tical phases. 

Diagrams  9  and  10  give  quantities  required  for  masonry,  concrete, 
and  concrete-steel  dams  of  different  heights  and  for  unit  length  of  ten 
feet;  the  cost  can  be  found  for  different  values  of  labor  and  material 
from  Diagram  11. 

The  dam  should  contain  waste-gates  or  sluices  and  perhaps  flash- 
boards,  which  must  be  covered  in  estimate. 

This  cost,  as  given  on  diagrams,  does  not  cover  the  construction  in 
river  bed  required  to  carry  the  dam,  safeguard  it  against  underwashing 
or  the  downstream  area  against  scouring.  In  soft  locations  a  pile  founda- 
tion, cut-off  walls  or  curtains,  and  apron  construction  will  be  required, 
the  extent  and  cost  of  which  depend  solely  upon  the  character  of  the 
material  on  which  the  dam  is  to  rest.  Again  reference  for  details  is 
invited  to  Part  II. 

Diagram  12  gives  quantities  for  foundation,  cut-off,  and  apron 
construction  in  alluvial  locations  for  different  heights  of  dams  and  for 
lengths  of  ten  feet. 

And,  finally,  the  dam  terminates  in  abutments,  unless  the  site  is  a 
rock  gorge  into  which  the  dam  structure  may  be  built;  Diagram  12  also 
gives  quantities  required  for  two  abutments  of  concrete-steel  design  for 
dams  of  different  heights. 

Compiling  the  cost  of  the  dam  in  alluvial  river  bed,  with  small  flow 
and  no  floods  during  construction  period,  height  above  river  bed  30  feet, 
length  between  abutments  250  feet,  labor  being  $0.20  per  hour,  material 
for  cub.  yd.  of  xxx  concrete  $4.75,  forming  timber  $25.00  per  1000  ft. 
b.  m.,  and  re-enforcing  steel  3c.  per  pound. 

Item  1.  Controlling  flow: 

Coffer-dam  or  sheet  piling $2,500.00 

Pumping,  200  days  at  $5.00 1,000.00 

Item  2.  Preparing  bed,  excavation,  etc 500.00 

Foundation,  cut-off  and  apron  dam: 

Rubble  masonry $36,300.00  or 

Cyclopean  concrete 28,117.00  or 

Concrete-steel 22,100.00 

Item  3.  Abutments 2,060.00 

Item  4.  Waste-  or  sluice-ways  and  gates  depending  upon  flood  flow  volume. 


45 


Height  of  Dam          30          35          40         45 


40 


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15 


.a 


Diagram    9 
Masonry  Dam 

Dimensions  and 
Quantities 


V 


50  ft. 

7 


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40 

35 
30 
25 
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15 
10 


Height  of  Dam   15 


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Buttresses  on 
14  ft.centers 


Diagram  10 
Concrete  Steel  Dam 


Height  of  Dam  10 


64 


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66 


COST   OF   DEVELOPMENT  67 

ARTICLE  24. — The  diversion  works,  by  which  the  water  is  carried 
from  dam  to  the  power  station,  are  next  in  line.  These  may  be  canal, 
flume,  or  pipe  line,  depending  upon  the  volume  and  distance  over  which 
the  water  must  be  conducted.  If  no  diversion  is  required,  these  are,  of 
course,  unnecessary.  These  structures  involve  excavation  of  rock  or 
loose  material,  timber  or  concrete  lining,  slope  paving,  timber  framing, 
wood  stave,  steel  plate,  or  concrete-steel  conduits,  pipe-line  anchorages, 
flume  supports,  intake  works,  head-gates,  culverts,  waste-  or  sluice-ways, 
and  gates  and  forebays  with  bulkheads,  all  of  these  being  treated  spe- 
cifically as  to  design  and  construction  in  Part  II. 

Excavation  cost  of  rock  depends  upon  its  character,  and  may  vary 
from  75  cents  to  $1.50  per  cubic  yard,  also  that  of  loose  material  from 
25  to  50  cents  per  cub.  yd. ;  timber  lining  of  canals,  with  timber  at  $20.00 
per  1000  ft.  b.  m.,  costs  $4.50  per  square  yard,  concrete  lining  $5.00  per 
sq.  yd.,  slope  paving  $1.25  per  sq.  yd.,  timber  framing  of  flumes  costs 
$40.00  per  1000  ft.  b.  m.  The  cost  of  pipe  line  at  present  is 

36-inch.  48-inch.  60-inch. 

Wood  stave $4.00  $6.00  $8.00 

Steel  plate " 6.00  8.00  10.00 

Concrete-steel 5.00  7.00               9.00 

per  linear  foot  of  pipe,  to  which  must  be  added  cost  of  delivery,  and 
putting  in  place,  painting,  etc. 

Cost  of  head-gates,  waste-  and  sluice-ways,  etc.,  depends  upon 
character  of  design  and  size  of  conduit. 

The  canal  prism  should  be  of  an  area  sufficient  to  pass  the  flow  at 
a  velocity  not  exceeding  three  feet  per  second;  the  diameter  of  pipe 
conduits  depends  upon  the  ratio  of  head  which  can  be  economically 
expended  in  friction.  The  designs  of  all  diversion  works  should  be  based 
upon  appropriate  hydraulic  theorems. 

ARTICLE  25. — The  power-house  is  the  last  of  the  principal  structures. 
Its  location  is  determined  by  the  development  programme;  it  may  be  at 
the  end  of  the  dam  or  inside  of  the  spillway,  immediately  below  or  at  the 
terminal  of  diversion  canal  or  pipe  line.  The  design  is  fixed  by  the  method 
of  bringing  the  water  to  the  turbines,  the  dimensions  by  number  of  power 
units  it  is  to  contain.  Whether  it  is  recommendable  to  let  the  water 
enter  the  power  station  freely  or  by  means  of  feed  pipes  depends  upon 
the  height  of  fall,  volume  of  flow,  and  topography  at  chosen  power- 
house site.  In  both  cases  the  structure  consists  generally  of  three  parts, 


68  HYDRO-ELECTRIC   PRACTICE 

—foundation,  substructure  or  pit,  and  superstructure  in  which  turbines 
and  generators  are  housed.  Foundation  must  adapt  itself  to  the  character 
of  the  material  at  the  site,  pit  to  volume  of  flow,  height  of  fall  and  of 
backwater,  and  superstructure  to  power  equipment.  The  walls  and  floors 
should  be  of  masonry,  monolithic  concrete,  or  concrete-steel.  Wherever 
permissible  the  water  should  be  taken  to  turbines  in  conduits,  as  the 
power-house  required  for  such  an  arrangement  will  be  considerably  less 
costly  than  where  the  water  enters  freely;  and,  for  the  same  reason,  if 
otherwise  recommendable,  the  power  units  should  be  rather  large  than 
small,  as  the  length  of  the  power-house  materially  depends  upon  this 
condition.  Especially  is  this  true  where  water  enters  freely,  since  the 
structure  in  that  event  performs,  in  a  sense,  the  functions  of  a  dam, 
and  the  foundation  and  pit  structures  must  in  that  case  be  designed  not 
only  for  the  duty  of  supporting  vertical  loads  but  also  to  resist  horizontal 
pressures,  which  adds  considerably  to  dimensions.  The  power-house 
should  be  readily  approachable  by  the  best  available  means  of  trans- 
porting the  heavy  equipment;  ample  room  should  be  provided  on  the 
operating  floor,  so  that  each  machine  can  be  readily  dismantled,  repaired, 
or  removed;  a  power  traveller,  by  which  parts  of  equipment  can  be 
handled,  should  be  provided.  There  should  be  no  stinting  of  light,  and 
the  roof  had  best  be  of  the  most  substantial  and  fire-proof  character. 

Diagram  13  gives  quantities  for  power-house  per  power  unit  length 
and  for  varying  heights  of  fall,  both  for  structures  into  which  water 
enters  freely  and  where  it  is  conducted  to  turbines  by  feed  pipes;  the 
same  diagram  shows  quantities  required  for  foundations  for  structures 
in  alluvial  locations. 

ARTICLE  26.— In  addition  to  these  works  there  may  be  required 
reservoir  embankments,  in  the  event  that  a  part  of  the  stream  valley  must 
be  closed;  in  fact,  this  is  the  most  frequent  condition.  These  embank- 
ments are  a  continuation  of  the  spillway,  but  rise  sufficiently  higher  to 
guard  them  against  possible  overflow,  the  spillway  proper  being  designed 
of  sufficient  length  to  pass  the  greatest  probable  flood  volume  at  a  safe 
height.  These  structures  may  be  of  earth  or  concrete-steel,  depending 
largely  upon  the  availability  of  suitable  material  for  the  former  type. 
Reservoir  banks  or  bulkheads  partake  of  the  importance  of  the  spillway, 
and  require  the  greatest  care  of  design  and  still  more  so  of  construction. 
This  consists  in  preparation  of  surface  on  which  they  are  placed  by  a 
complete  removal  of  all  vegetable  growth,  roots,  and  stones,  loosening 


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Quantities  in 
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69 


70  HYDRO-ELECTRIC   PRACTICE 

the  soil  to  a  considerable  depth;  constructing  a  core  wall,  which  must 
penetrate  into  impermeable  material,  and  compacting  the  material  of 
which  the  bank  is  to  be  constructed  in  thin  horizontal  layers  in  a  wet 
and  plastic  condition.  Core  walls  should  be  of  concrete  and  the  banks 
of  puddling  material,  being  a  proper  mixture  of  clay,  sand,  and  fine  gravel 
which  will  pack  solid  when  damp.  This  construction  involves  excavation 
at  25  to  50  cents,  concrete  at  $5.00  to  $6.00,  and  compacted  earth  fill 
at  35  to  50  cents  per  cub.  yd. ;  the  upstream  upper  slope  should  be  paved 
at  $1.25  per  sq.  yd. 

Diagram  14  gives  quantities  for  earth  reservoir  embankments  with 
concrete  core  wall  in  lengths  of  ten  feet  and  for  different  heights. 

Where  the  ground  material  is  hard,  reservoir  bulkheads  of  concrete- 
steel  construction  may  take  the  place  of  earth  embankments  when  suit- 
able material  for  these  is  not  available.  The  quantities,  in  ten-foot 
lengths,  are  given  on  Diagram  15. 

This  completes  the  works  which  are  generally  required. 

ARTICLE  27. — The  power  equipment  consists  of  water  turbines,  with 
governors  and  draft  tubes,  and  of  electric  generators,  exciters,  and 
switchboards.  When  generators  are  coupled  to  turbine  shafts  and  the 
units  are  of  standard  type,  an  estimate  of  $20.00  per  horse-power  will 
generally  cover  its  cost;  when  turbines  have  to  be  geared  to  generator 
shafts,  the  cost  per  horse-power  will  be  $24.00. 

ARTICLE  28. — The  last  item  comprises  the  transmission  line  and 
equipment.  As  a  rule,  a  wooden  pole  line  is  recommendable,  poles  being 
35  feet  long  and  set  106  feet  apart;  a  single  circuit  will  be  sufficient 
excepting  for  large  outputs.  Such  a  line  requires  cross-arms,  pins,  insula- 
tors, and  three  strands  of  bare  copper  wire,  the  size,  and  therefore  weight, 
of  which  depends  upon  the  amount  of  current  to  be  transmitted,  the 
voltage  of  transmission,  and  the  drop  or  loss  to  be  allowed.  On  lines 
up  to  50  miles  the  loss  may  be  economically  confined  to  10  per  cent. 

Diagram  16  gives  quantity  of  copper  wire  for  transmission  line,  for 
different  output  and  voltage,  at  5  per  cent,  line  drop,  per  mile,  to  which 
are  to  be  added  50  poles,  100  cross-arms,  150  pins  and  insulators,  for 
single  circuit  3-phase  line. 

Transformers  to  raise  and  lower  voltage  at  terminals  of  line  cost 
$6.00  per  kilowatt  of  output. 

A  substation  has  to  be  provided  at  market  end  of  line,  which  may 
be  estimated  for  at  $1.00  per  horse-power. 


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73 


74  HYDRO-ELECTRIC    PRACTICE 

ARTICLE  29. — The  probable  cost  of  the  development  may  be  com- 
piled from  these  approximations  by  finding  cost  of  dam  from  Diagrams 
9,  10,  11,  and  12,  cost  of  diversion  works  from  a  location  profile,  cost  of 
power-house  from  Diagrams  11  and  13,  cost  of  reservoir  structures  from 
Diagrams  11  and  15,  taking  cost  of  power  equipment  at  $20.00  per  horse- 
power, cost  of  transmission  line  from  Diagram  16,  and  cost  of  trans- 
formers and  substation  as  stated. 

To  these  items  must  be  added  10  per  cent,  for  engineering  and 
inspection,  and  to  the  total  the  value  of  lands,  right  of  way,  of  charter 
and  franchises. 


CHAPTER  V 

VALUE   OF   PROJECT    AND    PRESENTATION 

THE  SUMMING  UP  of  findings  from  investigations  of  market,  power 
capacity,  feasibility  and  practicability,  and  cost  of  a  hydro-electric 
project  takes  the  shape  of  an  engineer's  report,  with  such  documentary 
proofs  and  legal  opinions  as  conditions  may  call  for.  If  the  funds  re- 
quired for  development  are  to  be  secured  from  individual  investors  or 
through  the  customary  financial  channels,  by  which  the  securities  of  new 
enterprises  are  underwritten  and  placed  on  the  market,  the  make-up  of 
the  report  should  be  of  a  presentable  character,  preferably  in  bound 
book  form,  with  plans,  profiles,  and  designs  reduced  to  photographs. 
Such  a  report  is  here  given  in  full. 

ARTICLE  30. — Report  on  a  Hydro-electric  Project. — 

FREMONT  POWER  AND  LIGHT  COMPANY, 

FREMONT,  OHIO. 
GENTLEMEN: — 

In  accordance  with  your  commission,  I  have  secured  all  the  needed  data  to  report  to  you  on  the 
hydro-electric  power  development  on  the  Sandusky  River  near  your  city. 
My  conclusions  are  thus  summarized: 

This  project  contemplates  the  consolidation  of  four  old  mill  powers  and  the  modern  development 
of  the  opportunities  they  present. 

The  plan  is  feasible,  practical,  and  void  of  serious  or  costly  problems,  to  the  extent  of  developing 
a  marketable  output  of  twenty-two  hundred  electric  horse-power  and  delivering  the  product  for  dis- 
tribution at  Fremont,  O.,  for  about  one  hundred  thousand  ($102,600.00)  dollars;  the  required  invest- 
ment aggregates  one  hundred  and  seventy-five  thousand  dollars. 

Fremont,  O.,  offers  remunerative  market  for  the  output,  and  the  investment  will  earn  from  ten 
to  fifteen  per  cent  net. 

The  data,  calculations,  and  arguments  upon  which  these  findings  are  based  form  the  subject  of 
the  following  report. 

Yours  truly, 

(Signed)  H.  VON  SCHON, 
DETROIT,  MICH.,  October,  1905.  Consulting  Engineer. 

Hydrography. 

The  Drainage  Area. — Plan  1,  of  the  Sandusky,  is  of  the  Great  Lakes  system,  all 
of  it  being  in  the  State  of  Ohio.  Head-waters  are  in  Richland  County;  the  river 
empties  into  Sandusky  Bay  of  Lake  Erie. 

The  length  of  the  river  is* about  one  hundred  and  fifteen  (115)  miles;  the  drain- 
age area  tributary  to  the  point  here  considered  (Fremont,  Ohio)  covers  approximately 
fourteen  hundred  (1400)  square  miles. 

75 


76 


HYDRO-ELECTRIC   PRACTICE 


There  are  some  lakes,  of  small  areas,  at  the  source  of  the  river,  which  is  at  alti- 
tude of  twelve  hundred  and  eighty  (1280)  feet  above  sea  level.  The  basin  is  under- 
laid by  lime-rock  and  shale;  the  land  is  generally  under  cultivation;  the  wooded  area 
is  small. 

Precipitation,  evaporation,  and  run-off  are  those  normal  to  the  lower  Lake 
region;  the  annual  temperature  is  fifty  (50)  degrees. 

The  flow  has  not  been  established  by  authentic  measurements. 

Precipitation  has  been  observed  for  fifteen  years  at  three  (3)  points  in  the  water- 
shed concerned;  the  monthly  totals  from  1891  to  1905  are  given  on  Tables  1,  2,  and 
3,  and  the  monthly  means  for  the  drainage  area  for  same  period  on  Table  4.  (Here 
omitted.) 

The  fluctuations  in  annual  precipitation  are  shown  on  Profile  1.     (Omitted.) 

Evaporation  and  run-off  have  been  computed  for  the  two  dry  years  1894  and 
1905  of  this  period,  results  being  given  on  Tables  5  and  6,  and 

Monthly  flow  from  mean  run-off  of  these  dry  years  is  noted  on  Table  7  and 
shown  on  Profile  2.  (Omitted.) 

The  ground  flow  factor  used  in  these  calculations  is  that  established  for  water- 
sheds of  bold  relief,  with  light  drift  overlying  rock,  and  no  swamp  or  lake  storage. 

TABLE  5.— ORDINARY  DRY-YEAR  MONTHLY  RUN-OFF  FROM  SANDUSKY  RIVER 
WATER-SHED.     (All  measurements  in  inches.) 


PRECIPITATION. 

EVAPORATION. 

RUN-OFF. 

Ground 

MONTH  . 

Monthly. 

Total. 

Monthly. 

Total. 

Monthly. 

Total. 

Storage. 

December  '93  

2.34 

2.34 

0.65 

0.65 

1.69 

1.69 

full 

January  '94  

....    1.84 

4.18 

0.45 

1.10 

1.39 

3.08 

full 

February  '94  

2.48 

6.66 

0.55 

1.65 

1.93 

5.01 

full 

March  '94  

....    1.18 

7.84 

0.60 

2.25 

1.40 

6.41 

—0.82 

April  '94  

....   2.08 

9.92 

1.08 

3.33 

1.40 

7.81 

—1.22 

May  '94  

5.31 

15.23 

2.93 

6.26 

1.16 

8.97 

full 

June  '94  

3.86 

19.09 

3.47 

9.73 

1.32 

10.29 

—0.93 

July  '94  

....   2.70 

21.79 

3.81 

13.54 

0.46 

10.75 

—2.50 

August  '94  

....   0.69 

22.48 

2.79 

16.33 

0.28 

11.03 

—4.88 

September  '94  

3.26 

25.74 

2.28 

18.61 

0.22 

11.25 

—4.12 

October  '94  

.  .  .  .   3.50 

29.24 

1.30 

19.91 

0.28 

11.53 

—2.20 

November  '94  

....    1.81 

31.05 

0.84 

20.75 

0.40 

11.93 

—1.63 

December  '94  

2.31 

33.36 

0.65 

21.40 

0.68 

12.61 

—0.65 

T.=50°. 

Ground  flow 

for  minimum  capacity 

of  storage. 

Computed  by  H.  VON  SCHON,  Cons.  Engr. 

TABLE  6.— ORDINARY  DRY-YEAR  MONTHLY  RUN-OFF  FROM  SANDUSKY  RIVER 
WATER-SHED.     (All  measurements  in  inches.) 


MONTH.  Monthly. 

December  '04 3.78 

January  '05 1.56 

February  '05 1.43 

March  '05 0.94 

April  '05 2.94 


ATION. 

EVAPORATION. 

RUN-OFF. 

Ground 

Total. 

Monthly. 

Total. 

Monthly. 

Total. 

Storage. 

3.78 

0.80 

0.80 

2.98 

2.98 

full 

5.34 

0.43 

1.23 

1.13 

4.11 

full 

6.77 

0.44 

1.67 

0.99 

5.10 

full 

7.71 

0.58 

2.25 

1.32 

6.42 

—0.96 

10.65 

1.16 

3.41 

1.16 

7.58 

—0.34 

VALUE   OF   PROJECT  AND   PRESENTATION 


77 


78  HYDRO-ELECTRIC    PRACTICE 

TABLE  6.— ORDINARY  DRY-YEAR  MONTHLY  RUN-OFF  FROM  SANDUSKY  RIVER 
WATER-SHED. — Continued.     (All  measurements  in  inches.) 


MONTH. 

May  '05  

PRECIF 
Monthly. 

4.93 

TTATION, 

Total. 

15.58 
19.03 
23.79 
25.99 
28.88 
31.15 
33.54 
35.49 

EVAPORATION. 
Monthly.        Total. 

2.84           6.25 
3.36           9.61 
4.43         14.04 
3.17         17.21 
2.20         19.41 
1.15         20.56 
0.90         21.46 
0.61         22.07 

RuN-Orr 
Monthly.       Total. 

1.75          9.33 
1.20         10.53 
0.64         11.07 
0.38         1145 
0.32         11.77 
0.38         12.15 
0.68         12.83 
1.10         13.93 

Groum 
Storag 

full 

—1.11 

—1.32 
—2.67 
—2.30 
—1  56 
—0.75 
—0.51 

June  '05  

3.45 

July  '05  

4.76 

August  '05            

2.20 

September  '05  

2.89 

October  '05 

2.27 

November  '05  

2.39 

December  '05.  . 

.    1.95 

T.  =50°.      Ground  flow  for  minimum  capacity  of  storage. 

Computed  by  H.  VON  SCHON,  Cons.  Engr. 

The  fall  of  the  river  has  been  found  from  instrumental  levels  and  is  shown  on  Plan  3, 
The  elevations  (referred  to  sea  level)  of  points  pertinent  to  this  discussion  are: 

Sandusky  Bay 573  feet 

Lower  Rapids  (in  Fremont,  O.) 580  feet 

River  bed  at  Creager  power-house 585  feet 

River  bed  under  Ballville  bridge 590  feet 

Roadway  of  Ballville  bridge 613  feet 

River  bed  at  Cemetery  Hill 600  feet 

River  bed  at  Tucker  dam 609  feet 

Crest  of  Tucker  dam ". 618  feet 

River  bed  at  Tindall  bridge 627  feet 

Tindall  bridge  roadway 643  feet 

Sandusky  Falls,  upper  level 630  feet 

The  topography  of  river  banks  and  adjacent  territory  has  been  developed  instrument- 
ally  and  is  shown  on  Plans  3,  5,  and  6. 

Development  Programme. 

The  available  fall  is  fifty  (50)  feet  from  Upper  Sandusky  Falls,  at  elevation  of 
630  feet,  to  Lower  Rapids,  at  elevation  of  580  feet. 

To  utilize  this  fall  in  one  development  requires  diversion  of  river  by  a  canal  on 
south  side,  entailing  the  acquisition  of  the  right  of  way  and  the  withdrawal  of  prac- 
tically all  flow— during  low  stages— from  the  natural  river  bed,  by  which  property 
and  legal  difficulties  would  be  encountered. 

Forty  (40)  feet  of  the  available  fall  can  be  utilized  within  the  flowage  limits  of 
the  mill  powers  to  be  acquired,  and  without  change  of  natural  flow  in  river,  by  two 
developments, — a  twenty-two  (22)  foot  development  at  the  Cemetery  Hill  and  an 
eighteen  (18)  foot  development  at  the  Creager  power-house. 

The  remaining  fall  can  be  utilized  for  purposes  of  a  storage  reservoir. 

The  lower  development  to  be  at  the  Creager  power-house;  realizing  a  power  head 
of  eighteen  (18)  feet  by  deepening  tail-race  from  Lower  Rapids,  at  elevation  of  580 
feet,  to  river  bed  elevation  at  Creager  power-house,  585  feet,  and  erecting  .an  eleven 
(11)  foot  high  dam  with  two  (2)  feet  high  flashboards  rising  to  elevation  598  feet. 


VALUE   OF   PROJECT  AND   PRESENTATION 


79 


80 


HYDRO-ELECTRIC   PRACTICE 


SI 


82  ,       HYDRO-ELECTRIC    PRACTICE 

The  upper  development  would  be  at  the  Cemetery  Hill,  creating  a  power  head  of 
twenty-two  (22)  feet  by  erecting  a  twenty  (20)  foot  high  dam  on  river  bed,  elevation  of 
600  feet,  which,  with  two  (2)  feet  high  flashboards,  would  reach  an  elevation  of 
622  feet. 

A  storage  reservoir  could  be  created  on  the  Tindall  power  property  by  erecting 
on  the  river  bed  above  the  bridge,  at  elevation  627  feet,  a  six  (6)  foot  high  dam,  which, 
with  two  (2)  feet  high  flashboards,  would  rise  to  elevation  of  635  feet,  creating  a  reser- 
voir of  about  six  (6)  million  cubic  feet  capacity,  furnishing  a  ten-hour  flow  of  one 
hundred  and  sixty  (160)  cubic  second  feet,  which  could  be  increased  by  adding  flash- 
boards,  as  flowage  covers  to  elevation  of  638  feet. 


TABLE  7.— ORDINARY  DRY-YEAR  OUTPUT  OF  DEVELOPMENT  AT  FREMONT,  O.,  ON 

SANDUSKY  RIVER. 


Mean  of  1894  and 
Month. 

January  

RUN-O 
Water- 
1905,        shed, 
inches  e 
1      : 

1.26 

FP   FROM 

Square 
mile, 
ubic  sec.  ft. 
0.896 

1.12 
1.61 
1.21 
1.14 
1.30 
1.12 
0.49 
0.29 
0.24 
0.29 
0.48 
0.79 

Water- 
shed, 
square 
miles. 

1400 
1400 
1400 
1400 
1400 
1400 
1400 
1400 
1400 
1400 
1400 
1400 

Flow, 
cubic 
sec.  ft. 

1568 
2254 
1694 
1596 
1820 
1568 
686 
406 
336 
406 
672 
1106 

AVAILABLE 
Electric 
Horse-Power, 
Fall,        per  ft.               for  40 
feet            fall.                 feet. 

40         125.44          5017 
40         180.32          7212 
40         135.52          5420 
40         127.68          5107 
40         145.60          5824 
40         125.44          5017 
40           54.88          2195 
40           32.48          1299 
40           26.88          1075 
40           32.48          1299 
40           53.76          2150 
40           90.08          3603 

February  

1.80 

March  

1.36 

April      

1.28 

May  

1.45 

June  

1.26 

July           

0.55 

.August  

0.33 

September  

0.27 

October  

0.33 

November  

0.54 

December  .  . 

.   0.89 

Efficiencies:     turbines,  76  per  cent.;    generators, 

Compiled  by 

Market. 


90  per  cent. 

H.  VON  SCHON,  Cons.  Engr. 


The  proposed  development  is  half  a  mile  from  the  city  limits  of  Fremont,  O. 
(This  market  analysis  appears  in  Article  6.) 

Output. 

The  present  power  consumption  at  Fremont,  O.,  aggregates  2850  electric  horse- 
power, of  which  2050  ig  day  motor  (10  hour), 

250  is  light  (night),  and 
450  is  mixed  day  and  night  load. 

The  available  power  output  (see  Table  7)  is 

for  nine  months 2200  electric  H.P. 

for  eleven  months.  .e 1300  electric  H.P. 

for  twelve  months. .  1100  electric  H.P. 


VALUE  OF  PROJECT  AND  PRESENTATION 


84  HYDRO-ELECTRIC   PRACTICE 

The  recommendable  programme  appears  to  be  to  develop  twenty-two  hundred 
(2200)  electric  horse-power;  to  operate  the  plant  during  nine  months  with  continuous 
flow,  giving  24-hour  output  of  2200  electric  horse-power; '  during  three  months  of 
lower  flow  with  ten-hour  flow  doubled  by  night  storage,  yielding  a  10-hour  (day) 
output  of  2200  electric  horse-power;  and  to  supplement  for  night  service  with  250 
horse-power  steam  plant. 

Underlying  Values. 

1.  To  be  constructed. 

The  proposed  power  works  are  to  consist 

of  one  concrete  spillway  twenty-two  feet  high,  with  power-station  at  its  end; 
of  one  concrete  spillway  eleven  feet  high,  with  Creager  power-house  arranged 

for  station; 

of  one  concrete  spillway  six  feet  high; 
of  embankments  and  waste-flumes  to  empound  and  control  the  entire  flow 

of  the  river; 
of  the  hydraulic  and  electric  machinery  to  develop  the  water-power  and 

convert  it  into  electric  energy; 
and  of  the  transmission  line  by  which  the  current  is  to  be  delivered  to  the 

customers. 

The  total  cost  of  these  works  and  this  equipment  is  estimated  to  aggregate 
102,620  dollars. 

2.  Existing  properties  to  be  acquired 

consist  of  mill  powers  and  lands  controlling  the  flow  and  fall  of  the  river, 
the  necessary  pondage  and  storage,  and  the  sites  for  dams  and  power-stations. 

They  are 

(a)  The  Creager  water-power  property,  of  six  acres  of  land,  a  partial  timber 

dam,  an  obsolete  race-way,  and  a  substantial  mill  building,  with  some 
hydraulic  machinery  not  now  utilized  (lower  power  site). 

(b)  The  Heim  &  Baum  woollen  mill  property,  of  eleven  acres  of  land  and  a 

good  mill  building  not  occupied  at  present  (upper  power  site). 

(c)  The  Tucker  water-power  and  mill  property,  of  eleven  acres  of  land,  a 

timber  dam  now  in  commission,  serviceable  head-works  and  race-way, 
and  a  modern  flour  grist-mill  now  being  operated  by  water-power 
(upper  power  site). 

(d)  The  Tindall  mill  power,  consisting  of  eleven  acres  of  land  (reservoir  site)  ; 

and 

(e)  Some  twenty-seven  (27)  acres  of  bottom-land,  to  be  flooded  by  upper 

development. 

The  purchase  price  of  these  properties  aggregates  65,000  dollars. 


VALUE   OF  PROJECT  AND   PRESENTATION  85 

Inventory  of  Properties:   Buildings  and  Equipment. 

1.  Creager  property:  Valuation. 

One  four-story  slate-roofed  mill  building,  lately  used  as  a  power-house $3,500.00 

One  Samson  168  H.P.  water-wheel 250.00 

One  Leffel  104  H.P.  water-wheel 150.00 

One  Leffel  30  H.P.  water-wheel  (fair  condition) 50.00 

One  engine-house  and  100  H.P.  boiler  and  engine 1,000.00 

2.  Heim  &  Baum  property: 

Three-story  frame  woollen-mill 2,000.00 

Office  building 100.00 

3.  Tucker  property: 

Three-story  stone  mill  building 5,000.00 

Two  Leffel  water-wheels,  67  and  30  H.P.  respectively,  in  good  condition  . .  .  150.00 

Modern  milling  machinery  of  60  barrels  capacity,  good  condition 600.00 

One  70  H.P.  boiler  and  engine 1,500.00 

Stables  and  sheds 100.00 

Cooper-shop 100.00 

Total  valuation  of $14,500.00 

Structural  Types. 

Lower  Development. — Concrete  spillway,  on  rock,  11  feet  high,  300  feet  long; 
south  end  terminating  in  concrete-steel  abutment,  north  end  butting  against  masonry 
substructure  of  Creager  power-house. 

Earth  embankment,  300  feet  long,  connecting  south  abutment  with  natural 
bank  at  south  end  of  Ballville  bridge. 

Power  equipment  in  Creager  power-house. 

Upper  Development. — Concrete  spillway,  on  rock,  20  feet  high,  300  feet  long; 
south  end  against  rock  bank,  north  end  terminating  in  concrete-steel  abutment. 

Earth  embankment,  500  feet  long,  connecting  north  abutment  with  natural 
bank  at  Cemetery  Hill. 

Power  equipment  in  station  constructed  at  end  of  dam. 

Reservoir. — Concrete  spillway,  6  feet  high,  300  feet  long;  ends  terminating  in 
concrete-steel  abutments. 

Earth  embankments,  300  feet  long  on  south  and  200  feet  on  north  end,  connecting 
with  natural  banks. 

Estimates. 

Estimates  are  based  upon  following  unit  prices  not  quoted  in  connection  with 
schedules. 

Cement,  Portland,  delivered,  per  barrel $2.50 

Concrete,  1-3-6,  monolithic,  placed,  per  cub.  yd 6.00 

Concrete,  1-2-4,  cyclopean,  placed,  per  cub.  yd 7.00 

Concrete,  1-2-4,  formed  and  placed,  per  cub.  yd 8.00 

Excavation,  rock,  per  cub.  yd ,    0.75 

Excavation,  no  rock,  per  cub.  yd 0.30 

Gravel,  or  broken  stone,  for  concrete,  per  cub.  yd 1.00 

Labor,  per  day 1.75 


86 


HYDRO-ELECTRIC    PRACTICE 


Planking,  timber  for  forms,  per  M.  ft.  b.  m $25.00 

Sand  for  concrete,  per  cub.  yd 0.75 

Steel,  re-enforcing,  per  Ib 0.03 

Steel,  structural,  erected,  per  ton 100.00 

Team  and  driver,  per  day 3.50 

I.  Lower  Plant — Cr eager  Dam. 

Item    1.  Controlling  flow  by  diking $500.00 

Item    2.  Preparing  dam  site,  clearing 200.00  $700.00 

Item    3.  Foundation  on  rock  ledge. 

Item    4.  Spillway,  11  ft.  high,  300  ft.  long: 

810  cub.  yds.  cyclopean  concrete,  at  $7.00 5,670.00 

Item    5.  One  abutment,  concrete-steel: 

10  cub.  yds.  concrete,  at  $8.00 80.00 

700  Ibs.  re-enforc.  steel,  at  3  c 21.00  5,771.00 

Item    6.  Earth  embankments,  with  concrete  core,  20  ft.  15'  h.,  50  ft.  10'  h., 
300ft.  5'  h.: 

core  wall,  100  cub.  yds.  concrete,  at  $6.00 600.00 

1370  cub.  yds.  earth  fill,  at  $0.35 480.00  1,080.00 

Item    7.  Power  station  in  Creager  mill  for  two  power  units: 

2  pits  and  penstocks,  16'  x  20',  concrete-steel: 

280  cub.  yds.  concrete,  formed,  at  $8.00 2,240.00 

2000  Ibs.  re-enforc.  steel,  at  3  c 600.00 

Item    8.  Repairing  mill  building 1,000.00  3,840.00 

Item    9.  Deepening  tail-race,  2000  ft.  long,  25  ft.  wide,  5  ft.  deep  at  upper 
end: 

excavating  5000  cub.  yds.  rock,  at  75  c 3,750.00  3,750.00 

Item  10.  Hydraulic  equipment,  18  ft.  head,  400  cub.  ft.  flow,  four  33-inch 
turbines  with  draft  tubes,  two  per  unit,  at  330  H.P.,  180  R.p.m., 

placed,  at  $6.00  per  H.P 3,960.00 

Item  11.  Two  turbine  governors,  at  $300.00 600.00  4,560.00 

Item  12.  Electric  equipment: 

Two  250  Kw.  alternators,  2300  volts,  60  cycle  3-phase,  placed,  at 

$12.00  per  Kw 6,000.00 

Item  13.  Three  switchboards,  equipped,  at  $275.00 825.00 

Item  14.  Two  1\  Kw.  D.  C.  motors,  at  $250.00 500.00  7,325.00 

Lower  plant  complete $27,026.00 

II.  Upper  Plant — Cemetery  Hill  Dam. 

Item  15.  Controlling  flow  by  diking $500.00 

Item  16.  Preparing  spillway  site,  clearing 200.00  $700.00 

Item  17.  Foundation  on  ledge  rock. 

Item  18.  Spillway,  22  ft.  h.,  300  ft.  long: 

2475  cub.  yds.  cyclopean  concrete,  at  $7.00 17,325.00 

Item  19.  One  abutment,  concrete-steel: 

48  cub.  yds.  concrete,  at  $8.00 384.00 

2100  Ibs.  re-enforc.  steel,  at  3  c. 63.00         17,772.00 

Item  20.  Earth  embankment  with  concrete  core,  30  ft:  20'  h.,  20  ft.  15'  h., 
225  ft.  10'  h.,  225  ft.  5'  h.: 

core  wall,  242  cub.  yds.  concrete,  at  $6.00 1,452.00 

3330  cub.  yds.  earth  nil,  at  $0.35 1,166.00  2,618.00 


VALUE   OF   PROJECT   AND   PRESENTATION  87 

Item  21.  Power  station  for  2  units,  same  as  lower  station  with  addition  for 

roof  and  end  walls $8,000.00         $8,000.00 

Item  22.  Tail-race  in  river  bed  (none). 
Item  23.  Hydraulic  equipment: 

Four  30"  turbines  with  draft  tubes,  two  per  unit,  at  400  H.P., 

200  R.p.m.,  placed,  at  $6.00  per  H.P 4,800.00 

Item  24.  Two  turbine  governors,  at  $300.00 600.00  5,400.00 

Item  25.  Electric  equipment: 

Two  300  Kw.  alternators,  2300  volts,  60  cycle  3-phase,  placed, 

at  $12.00  per  Kw 7,200.00 

Item  26.  Three  switchboards,  equipped,  at  $275.00 825.00 

Item  27.  Two  10  Kw.  D.  C.  motors,  at  $275.00 550.00  8,575.00 

Upper  plant  complete $43,065.00 

III.  Reservoir  Dam  (Tindall). 

Item  28.  Controlling  flow $500.00 

Item  29.  Preparing  river  bed 200.00  $700.00 

Item  30.  Foundation  ledge  rock. 

Item  31.  Spillway,  6  ft.  h.,  300  ft.  long: 

300  cub.  yds.  cyclopean  concrete,  at  $7.00 2,100.00 

Item  32.  Two  abutments,  concrete-steel: 

12  cub.  yds.  concrete,  at  $8.00 96.00 

1000  Ibs.  re-enforc.,  at  3  c 30.00  2,226.00 

Item  33.  Earth  embankment  with  concrete  core,  100  ft.  10'  h.,  550  ft.  5'  h. : 

core  wall,  220  cub.  yds.  concrete,  at  $6.00 1,320.00 

2030  cub.  yds.  earth  fill,  at  $0.35 710.00  2,030.00 

Item  34.  Sluice-gate 500.00  500.00 

Storage  plant  complete $5,456.00 

IV.   Transmission. 
One  mile,  2300  volts,  1500  Kw.,  5  per  cent,  drop,  18,000  circ.  mils,  No.  6  wire. 

Item  35.  53  poles,  35  ft.,  set,  at  $5.00 $265.00 

Item  36.  116  cross-arms,  placed,  at  $0.50 53.00 

Item  37.  159  insulators,  placed,  at  $0.50 80.00 

Item  38.  1280  Ibs.  copper  wire,  at  $0.26 3,228.00 

Item  39.  Wire  strung,  at  $2.50  per  pole 132.00         $3,758.00 

V.  Distribution. 

Item  40.  Lines  (poles  in  place),  2  miles $6,986.00 

Item  41.  Transformers,  1500  Kw.,  at  $4.00 6,000.00 

Item  42.  Substation 1,000.00      $13,986.00 

Summary. 

Lower  plant 27,026.00 

Upper  plant 43,065.00 

Reservoir  plant 5,456.00 

Transmission 3,758.00 

Distribution 13,986-00 

Total 93,291.00 

Item  43.  Engineering  and  inspection,  10  per  cent 9,329.00 

Total  cost  of  development $102,620.00 


88 


Output. 


HYDRO-ELECTRIC   PRACTICE 


Generated. 2200  E.H.P. 

Delivered 2090  E.H.P.  or  1560  Kw. 

Cost  per  H.P.  delivered  for  service $49.10 

Annual  Operating  Cost. 
Generating,  Day  Service. 

One  operator,  supervising  both  plants $1,000.00 

Two  assistants,  at  $720.00 1,440.00 

Two  laborers,  at  $600.00 1,200.00         $3,600.00 

For  night  service  add  operator  and  2  assistants $2,440.00 

Distributing,  Day  Service. 

Superintendent 1,200.00 

Assistant 720.00 

Two  linemen,  at  $720.00 1,440.00 

Book-keeper 720.00 

Office  and  stationery 600.00          4,680.00 

For  night  service  add  assistant  and  one  lineman $1,440.00 

Maintenance  and  Depreciation. 

Works,  $60,000.00,  2  per  cent 1,200.00 

Equipment,  $32,000.00,  5  per  cent 1,600.00          2,800.00 

Taxes. 

2  per  cent,  on  §  valuation  of  lands  and  works,  $112,000.00 2,240.00 

Investment  Balance. 
Capital  investment: 

Property,  franchises,  etc $65,000.00 

Hydro-electric  plant 102,620.00     $167,620.00 

Charges. 

Item  1.  Interest  and  redemption  at  8  per  cent,  on  $175,000.00 14,000.00 

Item  2.  Operating  cost,  day  and  night: 

Generating 5,080.00 

Distributing 6,120.00 

Maintenance  and  depreciation 2,800.00 

Taxes 2,240.00         30,240.00 

Revenue. 

Item  3.  From  2090  H.P.,  1560  Kw.,  10-hour  service,  at  1}  c.  p.  Kw.  hr., 

with  75  per  cent,  load  factor, 

308  days — 3080  hours — 4,804,800  Kw.  hours,    OR 

3,603,600  Kw.  hours,  at  1$  c 54,054.00 

about  $26.00  p.  H.P. 

Surplus 23,814.00 

No  revenue  is  estimated  from  night  service;    operating  cost  estimate  includes  night  operation. 


ARTICLE  31.  Value  of  Hydro-electric  Opportunity. — The  value  of  any 
commercial  enterprise  is  deduced  from  the  value  of  its  product;  if  this 
is  not  marketable,  there  is  no  value.  Given  a  market  for  the  power  out- 
put of  a  hydro-electric  opportunity,  the  intrinsic  value  of  the  latter  must 


VALUE   OF   PROJECT  AND   PRESENTATION  89 

be  established  by  comparison  with  other  power  sources  from  which  the 
market  could  be  supplied,  and  it  becomes  purely  a  process  of  balancing 
the  comparative  earning  capacities  of  the  two  power  plants  and  the 
conversion  of  the  balance  into  the  principal  of  which  it  represents  the 
interest  or  cost  of  money. 

A  hydro-electric  plant  shows  on  estimates  an  annual  surplus  of 
$5000,  and  a  steam  plant  of  similar  output  pays  fixed  charges  and  no 
more;  it  is  evident  that  the  hydro-electric  opportunity  is  capable  of 
earning  interest  on  a  larger  investment  than  the  steam  plant;  the  theo- 
retical difference  is  $100,000,  and  the  intrinsic  value  of  the  hydro-electric 
plant  is  that  based  upon  the  rate  of  valuation  of  personal  property  for 
purposes  of  assessment  in  the  district  in  which  it  is  located.  Valuations 
of  lands  or  riparian  rights  representing  water-power  opportunities, 
determined  otherwise  than  from  a  conclusive  estimate  of  earning  capacity 
of  the  projected  plant,  are  purely  speculative  values,  which  may  be  a 
hundred  per  cent.,  and  greater,  in  error  either  way. 

Only  one  programme  gives  safe  results,  safe  commercially,  and  that 
is  to  secure  a  complete  and  correct  analysis  of  the  project. 


PART   II 

DESIGNING  AND  CONSTRUCTING  THE  DEVELOPMENT 

THIS  PART  treats  of  the  engineering  of  the  hydro-electric  develop- 
ment; in  it  are  presented  methods,  theories,  designs,  and  their  execution, 
as  they  have  been  found,  in  the  author's  practice  of  this  specialty,  to 
secure  the  desired  results  in  a  manner  adapted  to  the  commercial  as  well 
as  the  engineering  requirements  of  the  business.  Some  of  these  leave  the 
trodden  paths  of  former  practice;  the  majority  must  needs  follow  them; 
only  where  necessary,  in  the  author's  judgment,  to  make  clear  his  mean- 
ing, have  rudimentary  methods  been  employed;  on  the  whole,  it  has 
been  the  purpose  to  render  the  treatment  of  this  subject  complete  within 
its  scope. 

The  subheads  are  of  five  chapters  dealing  with  surveys,  development 
programme,  structural  types,  equipment,  plans,  and  estimates  and  speci- 
fications, construction,  and  superintendence,  each  of  which  is  divided 
into  articles  covering  detail  topics. 


CHAPTER  VI 

THE    SURVEY 

SURVEY  embraces  all  operations  by  which  the  hydrographic,  topo- 
graphic, and  geologic  characteristics  are  investigated  and  determined. 

ARTICLE  32. — The  first  preparation  for  the  work  of  surveys  is  the 
examination  of  maps  of  the  stream  and  the  projected  power-plant  loca- 
tion, if  such  has  been  fixed.  The  best  obtainable  maps  are  the  United 
States  Geological  Survey  topographic  sheets,  which  may  be  secured  from 
the  Director  of  the  Survey,  in  Washington,  D.  C.,  or  at  local  agencies. 
Several  of  the  States  provide  annual  appropriations  for  co-operative 
surveys  with  the  Federal  department,  and  the  annual  reports  of  the 
State  Engineers,  or  Geologists,  contain  topographic  county  maps  of 
similar  origin.  This  is  the  available  information  from  which  the  topogra- 
phy of  a  stream  system,  or  so  much  as  is  involved  in  the  examinations, 

90 


THE   SURVEY  91 

may  be  studied;  it  will  reveal  the  course  of  the  river,  the  contour  forma- 
tion of  its  banks,  its  fall,  by  the  crossing  of  successive  contours,  the 
locations  of  railroads  and  highways,  of  fords  and  ferries,  and  of  settle- 
ments. All  this  furnishes  ample  data  for  the  appreciation  of  the  general 
conditions,  which  will  become  useful  in  locating  dam  site,  estimating  fall, 
flowage  areas,  and  storage  opportunities. 

An  examination  of  the  drainage  area  on  State  maps  and  of  pre- 
cipitation records  will  throw  considerable  light  upon  the  probable  flow 
characteristics  of  the  watercourse;  note  the  origin  of  its  principal  sources, 
whether  in  foot-hills  or  flowing  out  of  swamps  or  lakes,  and  the  length 
of  its  tributaries,  the  import  of  all  of  which  will  be  discussed  in  detail 
further  on. 

Finally,  much  practical  information  as  to  subsurface  formations  in 
the  vicinity  of  the  projected  power  site  can  be  gained  from  well  borings; 
one  concern  frequently  operates  a  well-boring  apparatus  in  several  coun- 
ties, and  these  may  be  traced  through  hardware  merchants  at  the  county 
seat  or  near-by  town. 

ARTICLE  33.  Reconnaissance. — With  the  general  knowledge  of  hy- 
draulic, topographic,  and  geologic  characteristics  thus  gathered,  a  recon- 
naissance is  the  next  best  preparation,  on  horseback  or  preferably  in  a 
boat  floating  down  the  river,  equipped  with  a  camera,  compass,  hand- 
level,  aneroid,  field-glasses,  sketch-book,  and  the  plan  of  the  river's 
course,  showing  county,  township,  and  section  lines.  On  such  a  trip 
many  details  will  be  revealed  which  are  not  on  the  maps  or  are  given 
erroneously.  The  aneroid  should  be  read  at  regular  intervals  of  time, 
the  location  being  identified  on  the  map;  the  velocity  of  flow,  and  there- 
fore of  transit,  can  be  estimated  and  thus  distances  sufficiently  deter- 
mined to  aid  in  fixing  the  fall.  Observe  the  character  of  the  banks  and 
make  notes  in  the  sketch-book  of  likely  dam  sites,  estimating  the  river's 
width  and  finding  the  approximate  and  relative  heights  of  the  banks  by 
aneroid  and  hand-level;  note  also  the  improvements  on  river  bottom 
lands  and  the  height  of  bridge  crossings,  paralleling  railroads  and  high- 
ways. A  few  days  devoted  to  reconnaissance  will  prove  an  exceedingly 
valuable  investment,  the  benefits  of  which  will  be  frequently  recognized 
in  the  course  of  perfecting  the  development  programme;  above  all,  it  is 
highly  recommendable  to  make  copious  notes  and  sketches  of  whatever 
is  worth  remembering  and  to  take  photographic  views  of  the  most  notable 
features. 


HYDRO-ELECTRIC   PRACTICE 


Fig.  1 


ARTICLE  34.  Triangulation. — With  this  general  equipment  the  work 
of  definite  determinations  can  be  approached.  It  is  not  always  feasible 
to, foretell  what  the  extent  of  the  survey  will  be.  It  must  cover  the  dam 
site,  the  flowage  area,  and  perhaps  the  tracing  of  property  lines.  It  is, 
however,  always  advisable  first  to  establish  some  fixed  references  for 
elevations  and  points  by  a  system  of  triangulation  of  one  or  more  quad- 
rilaterals; this  should  be  planned  to  be  readily  accessible  and  safe  from 
interference  during  construction  and  above  the  highest  pond  level.  The 
base  should  be  at  least  twice  as  long  as  the  width  of  the  stream  valley. 

The  line  is  ins trumen tally  projected  and 
permanent  base-point  markers  of  stout 
posts  or  of  stones  are  set.  Measuring 
benches  (Fig.  1)  are  placed  at  intervals  of 
100  feet  along  the  line;  they  consist  of 
two  stout  vertical  stakes  set  twelve  inches 
centres  and  a  horizontal  piece  with  two- 
inch  flattened  top  face  secured  to  them; 
the  bench  pieces  of  each  successive  100- 
foot  section  are  on  same  level,  and  where 
this  changes  two  bench  pieces  are  secured 
to  stakes.  Supporting  brackets  (Fig.  1), 
consisting  of  a  stake  with  one  horizontal 
piece  at  the  level  of  the  respective  100- 
foot  section,  are  set  25,  50,  and  75  feet 
from  the  section  bench.  The  measurement 
should  be  made  with  a  standardized  100- 
foot  steel  tape,  which  is  placed  on  sup- 
porting brackets,  ends  on  benches,  and  a  ten-pound  weight  secured  to 
each  handle;  the  zero  is  marked  on  the  permanent  base  point  and  the 
fractional  foot  to  the  marked  centre  of  the  bench  piece  is  measured 
with  a  hardwood  scale  to  one-hundredth  of  a  foot;  record  of  the  length 
of  each  section  of  base  is  kept.  This  measurement  should  be  repeated 
three  times  and  the  mean  accepted.  The  selected  triangulation  points 
are  permanently  marked,  and  tripods  (Fig.  2),  constructed  of  fence- 
posts,  are  placed  securely  over  them,  the  legs  being  set  three  feet  in  the 
ground;  tops  are  covered  by  a  two-inch  wooden  plate  with  a  two-inch 
hole  in  its  centre  and  plumbed  over  the  base  point ;  the  top  of  the  tripod 
should  be  from  four  to  four  and  a  half  feet  above  the  ground.  Triangu- 


H.E.P.26 
H.V.S. 


Base  Benches;  Base  Supporting  Brackets. 


THE   SURVEY 


Fig".  2 


lation  points  are  preferably  marked  with  targets,  consisting  of  two  boards 
one  inch  thick,  twelve  inches  wide,  and  three  feet  long,  secured  to  each 
other  as  shown  in  Fig.  2,  wings  being  painted  alternately  white  and  red;  a 
two-inch  handle,  secured  to  the  end,  is  set  into  the  hole  of  the  tripod  plate. 

The  angles  should  be  measured  with  an  engineer's  transit  reading 
by  vernier  to  thirty  seconds.    The  instrument  is  secured  to  a  trivet  plate 
with  three  spikes  which  rest  on  the  tripod  plate.    Each  angle  should  be 
measured   five   times    in    both    direc- 
tions, giving  ten  readings;  the  mean  is 
accepted. 

The  azimuth  of  the  base  should  be 
determined  from  Polaris,  so  that  any 
station  in  the  survey  system  may  be 
available  for  the  tracing  of  the  mag- 
netic bearings  given  in  the  boundary 
descriptions.  The  sides  of  triangles 
are  computed  by  trigonometrical  func- 
tions; the  location  of  points  is  deter- 
mined by  co-ordinates. 

ARTICLE  35.  Elevations. — A  refer- 
ence bench  is  selected  or  established, 
and  the  elevations  of  the  triangulation 
points  are  determined  by  return  levels 
from  reference  or  line-benches  and 
plainly  marked  on  the  station  tripod. 
An  eigh teen-inch  "Y';  level  in  good 
adjustment  and  rods  reading  to  hun- 
dredths  of  a  foot  are  used  in  running 
the  level  lines.  Triangulation  benches 
being  established,  a  level  line  is  run  up  and  down  the  stream  over 
the  entire  reach  affected  by  the  development.  When  the  immediate 
river  shore  is  inaccessible  or  the  stream  tortuous,  the  line  may  follow 
along  the  top  of  the  bank,  or  at  some  distance  from  it  along  roads,  and 
levels  taken  to  water  at  accessible  points.  Every  fifth  turning-point  should 
be  a  bench  of  permanent  mark,  and  each  section  of  level  line  between 
benches  should  be  returned  until  an  agreement  between  two  runs  within 
0.001  foot  is  secured;  where  convenient  the  line  benches  should  be  con- 
nected with  the  triangulation  benches  for  check.  Elevations  are  plainly 
marked  on  all  permanent  benches. 


Tripod  and  Target. 


94 


HYDRO-ELECTRIC   PRACTICE 


ARTICLE  36.  Topography. — A  stadia  survey  is  made  of  all  the  river 
valley  to  be  considered  in  the  development;  it  is  referred  to  the  triangu- 
lation  system.  This  survey  should  develop  the  topography  to  one-foot 
contours  at  the  probable  location  of  the  works,  and  in  five-foot  contours 
over  the  remaining  territory;  the  bearings  should  be  of  azimuths  in 
harmony  with  the  triangulation  system;  distances  are  read  on  plumbed 
rods;  vertical  angles  are  measured  to  the  height  of  instrument;  stadia 

stations  are  marked  by  stakes  with  tack, 
and  the  instrument  is  plumbed.  When- 
ever practicable,  reference  readings  are 
taken  to  triangulation  and  water  points. 
By  this  survey,  with  a  rodman  on  each 
side  of  the  river,  the  shore  lines,  property 
corners  and  boundaries,  buildings,  bridges, 
roads,  and  a  sufficient  number  of  contour 
points  to  project  the  true  topography  are 
located.  Plan  7  shows  the  results  of  trian- 
gulation, levelling,  and  topographic  survey. 
The  instrument's  adjustments  should 
be  checked  at  the  beginning  and  close  of 
each  day's  survey. 

ARTICLE  37.  Phototopography.—Ii,  is 
not  the  purpose  to  enter  upon  a  broad  dis- 
cussion of  the  subject  of  photogrammetry, 
but  to  describe  only  the  practical  process 
by  which  a  general  projection  of  the  topo- 
graphy of  the  stream  valley  and  its  imme- 
diate high  banks  can  be  obtained  within 
contour  intervals  of  about  ten  feet. 


In  a  photographic  camera  (Fig.  3)  C  is  the  optical  centre,  being  the 
middle  point  of  the  optical  axis  between  the  two  lenses  of  the  objective; 
N  G  is  the  negative  plane  in  which  the  sensitive  plate  or  film  rests;  V  V 
is  the  optical  axis  produced  and  its  vertical  projection  called  the  vertical; 
H  H'  is  the  horizontal  projection  of  the  same  axis  known  as  the  horizon; 
C  V  is  the  focal  length  which  is  uniform  for  distances  beyond  100  feet; 
P  S  is  the  imaginary  positive  plane,  being  parallel  to  the  negative  plane 
and  focal  length  from  the  optical  centre. 

The  image  on  the  negative  plane  is  the  reverse  of  the  object  it  repre- 


THE   SURVEY 


95 


Fig.  4 


sents  and  in  true  perspective,  but  if  reflected  on  the  positive  plane  it 
would  there  appear  as  a  perfect  miniature  facsimile ;  the  points  F  and  F' 
in  the  negative  plane  would 
be  found  as  F  and  F'  in  the 
positive  at  like  distances  hor- 
izontally or  vertically  from 
the  vertical  or  horizon. 

This  is  the  optical  and 
geometrical  principle  on 
which  the  utilization  of  the 
camera  for  this  purpose  is 
based. 

Fig.  4,  A  B  D  E,  is  a 
print  of  the  negative  laid 
down  flat  with  H  H',  the 
reproduced  horizon,  parallel 
to  P  S,  the  positive  plane, 
and  at  any  convenient  dis- 
tance above  it;  V  V  is  the 
vertical  produced;  F  is  the 
image  of  a  flag  on  top  of  a 
hill.  To  locate  F  graphically 
drop-  a  perpendicular  from 
F  to  the  positive  plane  at  F' 
and  connect  this  point  with 
the  optical  centre  C,  fixed 
in  V  V  produced  and  focal 
length,  in  natural  scale,  from 
the  positive  plane.  The  true 
location  of  F  will  be  in  the 
extension  of  the  line  C  F', 
and  will  be  fixed  by  a  similar 
operation  with  the  second 
view  taken  from  the  other 
end  of  the  base  line,  as  the 
two  projections  will  intersect  at  the  location  of  F  in  the  plan. 

To  find  the  location  of  F  algebraically  measure  "y"  on  the  print, 
being  the  distance  along  the  horizon  of  the  vertical  projection  of  F  to 


H.E.P.29 
H.V.S. 


96 


HYDRO-ELECTRIC   PRACTICE 


the  image  vertical,  then  tg.  a  =  ^  (f  1  =  C  V  focal  length)  angle  a  +  b  is 

known  from  azimuths  of  triangulation  points,  so  is  the  length  of  the 
base  line  C  C'  and  therefore  also  lines  C  F  and  C'  F  which  are  plotted  in 
the  scale  of  the  base  line. 

In  this  manner  all  points  which  appear  on  two  views  can  be  located. 

To  -find  the  Elevation  of  an  Object  Algebraically. — Fig.  5,  A  B  D  E, 
is  the  positive  plane;  F  is  the  flag  the  elevation  of  which  is  to  be  deter- 
mined. Drop  the  perpendicular  F  L  to  the  horizon  and  connect  L  with 
C,  the  optical  centre,  measure  F  L  in  natural  scale  from  the  point;  then 


Fig.  5 


H.E.P.30 
H.V.S. 


C  L  (focal  length  in  natural  scale)  :  F  L  =  C  F'  :  F  F'  ;  C  F'  has  been 
found  as  per  preceding  discussion  and  is  expressed  in  the  scale  of  the 
base  line,  and  F  F  is  the  elevation  of  the  flag  point  above  the  horizon 
expressed  in  the  scale  of  the  base  line.  This  determination  can  be  re- 
peated from  the  other  view  containing  F,  thus  affording  a  valuable  check. 
For  F  the  elevation-  is  above  horizon  and  therefore  to  be  added  to  H  I, 
height  of  instrument  or  its  elevation;  for  M,  being  below  the  horizon, 
the  reverse  is  the  case. 

To  find  the  Elevation  Graphically. — Fig.  6,  A  B  D  E,  is  the  positive 
print,  F  the  image  of  the  flag,  P  S  the  positive  plane,  C  N  the  focal  length ; 
drop  a  vertical  from  F  to  the  positive  plane  in  F',  connect  C  with  F'  and 
produce  to  F  as  per  previous  discussion  in  the  scale  of  the  base  line; 
measure  x,  the  height  of  the  flag  point  above  the  horizon,  on  the  print, 


THE   SURVEY 


97 


Fig.  6 


draw  a  perpendicular  to  C  F  at  F  equal  to  x  in  the  scale  of  the  print, 
then  C  F'  :  x  =  C  F  :  x',  which  is  the  height  of  the  flag  point  above  the 
horizon  measured  in  the  scale  of  the  base  line. 

The  practical  operating  programme  is  as  follows: 

The  camera  is  attached  to  an  engineer's  transit  by  means  of  screw 
hooks  fixed  on  the  side  of  one  of  the  standards,  and  two  lugs  or  sleeves 
correspondingly  spaced  are  secured  to  the  side  of  the  camera  box. 
When  the  camera  is  thus  suspended  from  the  transit  standard  and 
the  latter  is  levelled  up,  the  following  conditions  are  met: 

1.  The  optical  centre  of  the   camera 

objective  lies  in  a  vertical  plane 
over  the  station  point  occupied 
by  the  transit. 

2.  The  optical  camera  axis  is  in  a  ver- 

tical plane  parallel  to  the  optical 
transit  telescope  axis. 

3.  The  optical  camera  axis  lies   in  a 

horizontal  plane  with  the  transit 
telescope  revolving  axis. 

4.  The  negative  plane  is  vertical. 
These    four    conditions    remain    rigid 

throughout  the  operations  here  considered — 
that  is,  the  more  complex  and  broader  prac- 
tice of  photogrammetry  in  which  the  nega- 
tive plane  may  be  inclined  from  the  vertical 
or  of  curved  surfaces  does  not  here  enter. 


H.E.P.31 
H.v.S. 


Any  commercial  camera  can  be  employed  with  satisfactory  results, 
the  lighter  the  better;  a  5  x  7  is  well  adapted;  the  objective  should  be 
rectilinear  and  the  focal  length  uniform  for  distant  points. 

The  vertical  and  horizon  are  marked  on  the  ground  glass  or  finder, 
and  small  arrows  or  pointers  are  fixed  to  the  interior  of  the  four  sides  of 
the  plate  or  film  holder  at  the  intersections  of  vertical  and  horizon  with 
the  frame,  so  that  each  view  taken  bears  these  marks,  by  which  the  control 
lines  can  be  correctly  reproduced  on  the  positive  print.  The  apparatus 
is  now  ready  for  operations, — that  is,  the  survey  of  a  stream  valley,  a 
triangulation  system  having  been  established. 

5.  The  instrument  is  set  over  a  triangulation  station,  the  camera 
attached,  and  the  transit  levelled. 

7 


OF  THE 

UNIVERSITY 

OF 


98  HYDRO-ELECTRIC   PRACTICE 

6.  A  pointing  is  made  with  the  transit  and  known  azimuth  to  the 

triangulation  target  on  the  opposite  side  of  the  stream  valley. 

7.  The  plate  or  film  is  exposed,  removed,  and  the  camera  is  re- 

charged. 

Sweeping  the  horizon  in  the  direction  of  the  operating  programme, 
up  or  down  stream,  one  pointing  is  made  and  view  taken  to  each  visible 
opposite  triangulation  target. 

8.  A  record  is  kept  as  in  surveys,  views  being  identified  as  1  to  2, 

1  to  4,  1  to  6,  etc.,  and  the  same  notation  is  made  on  the  plate 
holders  as  they  are  taken  from  the  camera. 

The  same  programme  is  repeated  from  the  opposite  side, — that  is, 
2-1,  2-3,  2-5,  etc. 

The  operator  needs  no  technical  photographic  knowledge  or  skill 
beyond  adjusting,  charging,  and  unloading  the  camera,  protecting  plates 
from  being  light-struck,  guarding  against  halation, — that  is,  exposures 
toward  the  sun, — and  a  practical  guide  to  the  use  of  the  proper  diaphragm 
or  stop  and  the  length  of  exposure  under  different  conditions  of  light  and 
time  of  day.  Such  an  exposure  and  diaphragm  scale  should  be  adapted 
to  the  characteristics  of  the  objective  and  the  sensitiveness  of  the  plate, 
and  the  data  required  can  readily  be  obtained  from  the  photographic 
supply  house  where  these  are  secured. 

Development  of  the  exposed  plates  or  films  and  the  printing  of  the 
positives  had  best  be  delegated  to  a  photographer.  In  practice  it  will 
be  found  advisable  to  duplicate  all  views,  to  make  certain  by  examination 
of  image  on  ground  glass  or  in  finder  that  the  key  point  connecting  with 
the  previous  view  is  in  the  field  of  view.  The  instrument  must  be  exam- 
ined before  each  exposure  as  to  its  level  condition,  as  the  weight  of  the 
camera  may  throw  it  out.  The  prints  should  be  strong,  and  in  order  to 
secure  detail  an  orange-colored  screen  may  be  fixed  in  the  camera  imme- 
diately back  of  the  objective. 

9.  For  the  projection  of  the  plan  the  horizon  and  vertical  are  drawn 

on  the  prints  in  vermilion,  and  likewise  all  objects  to  be  plotted 
are  marked  by  small  circles  or  dots  of  the  same  color  and  num- 
bered identically  on  the  different  prints  containing  them. 
After  the  principal  points  are  projected  and  their  elevations  have 
been  determined,  the  contours  and  topographic  characteristics  are  plotted 
on  the  plan  as  indicated  in  the  prints. 

As  stated  at  the  beginning  of  this  subject,  the  results  to  be  expected 


THE   SURVEY 


99 


are  of  a  general  character  only,  and  therefore  the  refinements  of  guard- 
ing against  change  of  paper  texture  have  no  place  here. 

ARTICLE  38. — Detail  surveys  should  be  made  of  gauging  sections, 
recommendable  dam  sites,  and  of  the  location  of  the  diversion  works; 


they  are  referred  to  bench  marks  by  determination  of  land  or  river  bed 
and  of  water  surface  elevations  at  intervals  of  five  feet  by  means  of  "  Y" 
level,  the  points  in  the  river  being  taken  from  a  boat  passing  across  along 
a  line  held  taut  by  means  of  upstream  guy  ropes,  the  line  being  suitably 
marked  off  in  five-foot  lengths.  One  such  section  suffices  at  the  gauging 
point,  the  terminals  being  fixed  by  posts;  gaugings  of  different  days 


100 


HYDRO-ELECTRIC   PRACTICE 


Fig.  8 


Reference  Level 


should  be  preceded  by  re-sectioning  in  order  to  detect  changes  in  the 
river  bed.  At  the  dam  locations  a  section  of  the  stream,  two  hundred 
feet  long,  should  be  covered  by  transverse  lines  five  feet  centres;  canal, 
flume,  and  pipe  line  locations  must  be  cross  sectioned  every  ten  feet 
longitudinally  for  a  width  double  that  of  the  probable  construction,  the 
centre  line  being  traversed  and  marked  at  100-foot  points.  The  power- 
house location  site  should  be  cross  sectioned  as  described  for  the  dam  site. 

Fig.  7  shows  the  plan  and  cross-section 
of  a  dam  site. 

ARTICLE  39. — Borings  should  be  made 
on  sites  of  dam,  diversion  works,  and  power 
station,  being  carried  to  rock  or  imperme- 
able material,  and  about  fifty  feet  centres 
in  each  direction.  The  elevation,  depth, 
and  character  of  each  class  of  material 
should  be  ascertained.  The  stratifications 
of  rock  for  upper  ten  feet  of  its  depth  must 
be  ascertained  in  order  to  discover  possible 
water  channels,  nor  must  the  rock  surface 
found  at  fifty-feet  points  be  accepted  as 
being  uniformly  level  between  them,  but 
intermediate  borings  should  be  made  to 
establish  fully  these  conditions.  Gravel, 
clay,  and  sand  should  be  classified  as  to 
their  characteristics,  samples  of  all  being 
preserved  for  future  reference.  These  in- 
vestigations by  borings  cannot  be  made 
too  exhaustively;  the  more  thorough  the 
knowledge  of  the  subsurface  formations, 
the  better  for  the  sake  of  safety  and  economy.  A  well-digger's  outfit 
will  prove  the  best  for  all  purposes;  nothing  of  much  value  can  be 
secured  with  hand-boring  apparatus.  All  borings  should  be  instrumen- 
tally  located  and  all  elevations  referred  to  bench  marks. 
Fig.  8  shows  the  record  of  a  boring  station. 

ARTICLE  40. — Stream  gaugings  should  be  made  daily  for  as  long  a 
period  as  practicable,  which  will  employ  a  separate  force  of  three  or 
four  men  constantly.  A  well-conditioned  section  is  selected,  preferably 
on  a  straight  reach  of  the  river,  the  best  obtainable  being  a  bridge  cross- 


Clay  &  Sand 


Gravel  &  Clay 


travel  &  Boulder 


Rock 


THE   SURVEY 


101 


ing,  and  in  its  absence  a  point  where  the  perimeter  is  of  nearly  uniform 
elliptical  shape  and  the  flow  is  not  influenced  by  islands,  shoals,  rocks, 
or  other  obstructions.  A  gauge  is  set  at  each  shore  point,  preferably  in 
a  recess  of  the  shore  where  it  will  be  guarded  against  floatage ;  it  consists 
of  a  board  graduated  to  feet  and  tenths,  which  is  secured  to  a  post  or 
pile  firmly  set,  or  to  a  bridge  pier.  The  gauge  boards  are  marked  to 
correspond  with  the  elevation  reference  of  the  survey.  The  cross-section 
is  determined  as  described  in  Art.  37.  Gauges  are  read  and  a  velocity 
measurement  is  made  with  a  current  meter.  The  programme  will  depend 
upon  conveniences  at  hand,  most  readily  from  a  flat  boat  passing  across 
by  aid  of  a  ferry  rope  or,  better,  from  two  such  boats  secured  together 
by  a  timber  platform.  The  meter  must  be  rated  before  and  after  the 
operation,  which  is  most  conveniently  done 
by  having  two  meters,  one  of  which  is  used 
only  as  the  standard,  all  the  measurements 
being  made  with  the  other.  Velocity  meas- 
urements should  be  made  at  depth  inter- 
vals of  two  feet;  if  the  river  stage  fluctu- 
ates during  measurements,  they  should  be 
rejected.  The  meter  is  used  from  the  up- 
stream end  of  the  boat;  three  separate 
readings  of  one,  one  and  a  half,  and  two 
minutes'  duration  should  be  taken  for  each 
observation,  and  the  mean  accepted;  the 
boat  must  be  held  firmly  in  a  fixed  position  during  the  observations. 
The  measurements  at  all  the  verticals  of  one  meter  station  are  to  be  made 
before  moving  to  the  next  station  in  the  section.  The  first  measurement 
should  be  taken  two  feet  below  the  surface;  the  last,  two  feet  above  the 
river-bed,  and  at  least  three  on  each  vertical.  In  great  depths,  or  swift 
currents,  a  sufficient  weight  must  be  suspended  from  the  meter  to  main- 
tain it  in  a  vertical  position.  Weeds  and  floating  sand  will  interfere  with 
correct  measurements. 

The  total  discharge  is  ascertained  by  plotting  the  velocities  found 
for  each  vertical  as  shown  in  Fig.  9,  where  S'  F  represents  the  verticals 
and  total  depth,  a',  b',  c',  d',  e'  the  meter  points  2  feet  centres,  and 
a'  a,  b'  b,  c'  c,  d'  d,  and  e'  e  the  corrected  velocities  for  each;  there- 
fore the  discharge  through  section  S'  F  is  represented  by  the  area 
S'  S  a  b  c  d  e  F. 


102 


HYDRO-ELECTRIC    PRACTICE 


Fig.  10  represents  the  entire  cross-section;  1,  2,  3,  4,  etc.  are  section 
points  ten  feet  centres;  the  lower  ordinates  express  the  depth,  the  upper 
the  mean  velocities;  the  discharge  at  a  section  point  =  d  x  v,  and  the 
total  discharge  is  the  product  of  the  sum  of  all  point  discharges  into 
ten,  their  spacing. 

Meters  should  be  run  for  a  short  time  before  beginning  the  operations, 
—i.e.,  before  readings  are  taken, — as  they  are  likely  to  overspeed  at  first. 

When  current  meters  are  not  available,  the  velocity  may  be  found 
by  aid  of  floats.  The  gauging  station  is  arranged  as  described  in  Art.  16; 


Fig.  10 


H.E.P.35 
H.V.S. 


surface  floats,  preferably  corked  bottles  sufficiently  weighted  to  project 
only  with  their  necks,  are  placed  in  the  water  fifty  feet  above  the  up- 
stream gauging  section  limit,  being  the  "dead  run,"  the  locus  of  their 
passage  into  the  gauging  section  area  is  noted  by  line  markers,  and  the 
time  of  such  entry  is  taken  by  a  stop-watch;  one  satisfactory  run  should 
pass  under  each  marker;  the  bottles  may  be  recovered  by  a  boat  below 
section.  Subsurface  floats,  or  double  floats,  are  sometimes  employed; 
they  consist  of  a  surface  float  from  which  a  lower  float  is  suspended,  the 
theory  being  that  thus  the  velocity  of  lower  strata  will  be  indicated;  in 
practice  this  result  is  not  readily  realized. 

Rod-floats  are  likely  to  secure  a  much  more  reliable  measurement  of 
mean  velocity  of  the  stream.    They  are  one-inch  square  soft  wood  sticks 


THE   SURVEY  103 

weighted  at  one  end  with  lead  strips  or  wire  to  float  upright  and  as  near 
the  bottom  of  the  river  as  practicable  without  striking  it;  they  are  set 
adrift  fifty  feet  above  the  section,  being  located  and  timed  as  are  surface 
floats;  one  should  be  sent  under  each  line  marker. 

ARTICLE  41.  Reduction  of  Stream  Gaugings. — The  discharge  of  a 
watercourse  is  the  product  of  its  area  and  the  velocity  of  flow ;  the  former 
having  been  found  from  cross-section  and  the  latter  by  any  of  the  de- 
scribed methods. 

When  surface  floats  are  employed,  the  observed  velocity  is  the 
surface  velocity,  which  is  reduced  to  the  mean  velocity  and  then  plotted, 
as  in  Fig.  10,  for  the  respective  vertical.  The  ratio  of  surface  to  mean 
velocity  is  fixed  by  the  depth  and  the  coefficient  of  the  perimeter  rough- 
ness, "  N,"  which  for  alluvial  stream  beds  is — 

.017  for  a  smooth  channel  bed  without  any  obstructions  to  flow, 

such  as  boulders,  snags,  or  large  gravel  in  bed; 

.020  for  smooth  channels  with  large  gravel  in  bed; 

.0225  for  slightly  irregular  channel  beds; 

.025  for  an  irregularly  contoured  bed  with  some  boulders; 

.0275  for  same  as  last  with  boulders  and  some  weeds; 

.030  for  rough  rock  channel  beds ; 

.035  for  very  rough  rock  beds  with  many  boulders. 

With  these  values  of  "N"  for  the  respective  channels,  the  compiled 
results  of  many  experiments  suggest,  as  an  approximate  ratio  of  mean 
to  surface  velocities,  the  values  given  on  Diagram  17;  when  the  mean 
velocity  on  a  vertical  has  thus  been  found  from  the  observed  surface 
velocity  it  is  plotted  as  shown  on  Fig.  10. 

The  velocities  of  rod  floats  represent  the  mean  velocity  of  a  vertical 
section  when  their  submerged  length  is  0.99  of  the  depth  of  the  water; 
but  it  is  impracticable  to  float  them  of  such  length,  and  their  velocities 
are  therefore  in  excess  of  the  mean  velocity;  the  necessary  corrections, 
as  established  by  experiments,  are  given  on  Diagram  18. 

ARTICLE  42.  Stream  Discharge  Curve. — When  the  river's  discharge 
is  known  for  a  considerable  range  of  its  stages,  a  discharge  curve  is  pro- 
jected, as  shown  on  Diagram  19,  by  which  the  flow,  corresponding  to 
any  gauge  height,  can  be  found;  only  constant  repetitions  of  stream 
measurements,  especially  during  the  extreme  low  and  high  stages,  will 
furnish  the  complete  data  for  a  reliable  rating  of  its  flow. 


Diagram  17 
Flow  Measurement 


Surface  to  Mean 
Velocity 


Ritio  of  nean  to  surface  velocity 


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THE   SURVEY 


107 


ARTICLE  43. — When  the  stream  is  small,  it  may  be  practicable  to 
ascertain  the  flow  by  weir  measurement. 

Fig.  1 1  shows  the  elevation  and  section  of  a  weir,  being  a  rectangular 
opening  of  horizontal  base  and  vertical  ends,  the  edges  of  the  weir  crest 
and  ends  being  wedge  shaped.  The  weir  crest  should  be  of  such  height 
that  the  downstream  water  surface  is  below  it.  The  theory  of  measuring 
the  volume  passing  over  the  weir  is  based  upon  the  law  of  velocity  of 
flow  discovered  by  Torricelli,  to  wit:  "the  theoretic  velocity  of  the  flow 
of  water  is  like  that  of  a  body^alling  freely  in  a  vacuum  through  a  height 
equal  to  the  head,"  -  V=^2  gh,  where  V  is  velocity  in  feet  per  second, 
g  is  acceleration  of  gravity,  32.2  feet  per  second,  and  h  is  the  head  or 
height  of  water  above  the  weir  crest. 


Fig.  11 


H.E.P.39 
H.v.S. 


In  Fig.  11,  C  is  the  weir  crest,  S  the  surface  of  the  water;  each  film 
of  water  passes  with  a  velocity  due  to  the  head  acting  upon  it, — i.e.,  of 
0.1,  0.2,  0.3,  etc.,  feet  down  to  the  lowest  film,  the  one  near  the  crest,  the 
velocity  of  which  is  that  due  to  S  C  =  h.  Were  the  respective  film  veloci- 
ties projected  as  ordinates  a  a',  bb',  c  c',  d  d',  etc.,  they  would  terminate 
in  a  parabolic  line  S  a'  b'  c'  d'  e'  P,  and  the  volume  passing  in  a  unit  of 
time  would  be  represented  by  the  parabola  segment  S  P  C.  In  accordance 
with  the  geometric  theorem,  the  area  of  this  segment  is  two-thirds  of  the 
rectangle  of  like  base  and  altitude,  orSPC  =  §hx-y/2gh,  which  there- 
fore expresses  the  theoretic  volume  passing  over  the  weir. 

This  value  is  based  upon  the  free  falling  of  the  water  in  a  vacuum, 
and  the  actual  volume  will  therefore  be  reduced  from  this  theoretic  by 
reason  of  the  friction  of  water  against  the  weir  crest  and  ends  and  against 
the  air,  all  of  which  retarding  influences  are  expressed  by  coefficients 


108  HYDRO-ELECTRIC   PRACTICE 

which  have  been  determined  from  results  of  many  experiments.  End 
contractions  are  expressed  by  J.  B.  Francis  in  a  reduction  of  length  "L" 
of  weir  =  0.1  h  for  each  such  contraction,  while  the  other  reductions 
from  the  theoretical  volume  are  expressed  by  the  same  authority  by  a 

coefficient 

M  =  0.622. 

More  recent  determinations  by  M.  H.  Bazin  differ  slightly  from  this. 
The  weir  formula  is  then 


Q  (discharge)  =M§h^2gh  X  (L-0.2hL). 
Solving,  Q  =  0.622  X  §8.02h  Vh  X  (L-0.2hL). 


When  L  exceeds  5  h  the  correction  for  end  contractions  may  be 
omitted,  and  for  the  purposes  of  stream  measurements 

Q  =  3.33  \/h3  per  linear  foot  of  weir, 

where  "h"  represents  the  height  of  water  on  the  weir  crest  measured 
at  a  point  upstream  of  the  weir  and  above  the  initial  depression  due  to 
the  overfall. 

Diagram  2  is  constructed  from  this  formula. 

ARTICLE  44.  Flow  deduced  from  Precipitation  and  Evaporation.  — 
When  flow  measurements  are  insufficient  to  yield  a  rating  curve,  espe- 
cially when  the  low  flow  remains  uncertain,  the  only  method  by  which 
an  approximation  of  it  can  be  found  is  by  the  deduction  of  the  run- 
off as  the  difference  between  the  precipitation  and  evaporation.  The 
general  theory  on  which  this  method  is  based  has  been  outlined  in 
Art.  16,  Part  I.  The  detail  operations  of  its  practicable  application 
are  as  follows: 

Evaporation  computations  are  based  upon  the  determined  monthly 
ratios  due  to  the  requirements  of  vegetation,  the  capacity  and  condition 
of  ground  storage,  and  the  temperature.  The  year,  for  this  purpose,  is 
divided  into  two  periods,  the  first  being  from  December  to  May,  when 
vegetation  needs  but  little  moisture  and  the  evaporation  is  only  that 
due  to  the  action  of  the  sun;  during  these  six  months  evaporation  is  small 
and  fluctuates  only  with  precipitation  or  is  very  similar  to  evaporation 
from  water  surfaces.  The  quantity  of  evaporation  during  this  period  is 
approximately  expressed  by  E  =  4.20  +  0.12  R,  in  which  "E"  represents 


THE   SURVEY  109 

total  evaporation  and  "R"  total  precipitation  during  this  period.  The 
second  period  is  from  June  to  November,  when  vegetation  matures  and 
requires  a  large  amount  of  moisture;  this  is  generally  expressed  by 
E  =  11.30  +  0.20  R. 

The  monthly  distribution  of  these  quantities  is  given  by  the  fol- 
lowing values: 

For  December e  =  0.42  +  0.10  r 

For  January e  =  0.27  +  0.10  r 

For  February e  =  0.30  +  0.10  r 

For  March e  =  0.48  +  0.10  r 

For  April e  =  0.87  +  0.10  r 

For  May e  =  1.87  +  0.20  r 

For  June : e  =  2.50  +  0.25  r 

For  July e  =  3.00  +  0.30  r 

For  August e  =  2.62  +  0.25  r 

For  September e  =  1.63  +  0.20  r 

For  October e  =  0.88  +  0.12  r 

For  November e  =  0.66  +  0.10  r 

"e"  is  monthly  evaporation,  "r"  monthly  precipitation. 

These  values  were  found  substantially  correct  for  the  latitude  of 
New  Jersey,  while  for  others  a  temperature  correction  is  to  be  applied. 
Five  per  cent,  for  each  degree  of  temperature  as  differing  from  that 
normal  in  the  latitude  above  referred  to  appears  to  correct  these  values 
for  stream  systems  in  other  latitudes,  and  it  is  sufficient  to  apply  this 
correction  as  based  upon  the  mean  annual  temperature  of  the  drainage 
area  in  question,  which  correction  is  expressed  by  0.05  T—  1.48,  in  which 
"T"  is  annual  temperature;  this  may  be  termed  the  temperature  factor, 
with  which  the  values  above  given  for  monthly  evaporation  are  to  be 
multiplied. 

ARTICLE  45. — A  typical  case  of  flow  determination  will  now  be  taken 
up  and  argued  month  by  month  to  its  conclusion.  The  river  taken  is 
the  Maitland  in  Ontario,  emptying  into  Lake  Huron  at  Goderich,  which 
was  examined  by  the  author  in  1905,  the  flow  being  measured  for  a  suffi- 
cient period  to  prove  substantial  agreement  between  the  two  methods. 
The  year  taken  is  1903.  Monthly  precipitation  records  were  available 
for  five  well-distributed  stations  in  the  area,  and,  as  the  stream  flows 
generally  westerly  and  its  drainage  area  is  located  in  one  precipitation 
belt,  the  monthly  mean  of  all  stations  was  adopted. 

The  mean  annual  temperature  was  found  to  be  46°  F. 

Temperature  factor  0.05  X  46  -  1.48  =  0.82. 


110  HYDRO-ELECTRIC   PRACTICE 

Month.  Precipitation.  Evaporation. 

December  '02 2.18  (0.42  +  0.10  r)  X  0.82  =  0.52 

January  '03 1.36  (0.27  +  0.10  r)  X  0.82  =  0.33 

February  '03 1.80  (0.30  +  0.10  r)  X  0.82  =  0.39 

March  '03 1.19  (0.48  +  0.10  r)  X  0.82  =  0.49 

April  '03 0.89  (0.87  +  0.10  r)  X  0.82  =  0.79 

May  '03 2.74  (1.87  +  0.20  r)  X  0.82  =  1.98 

June  '03 2.85  (2.50  +  0.25  r)  X  0.82  =  2.63 

July  '03 2.68  (3.00  +  0.30  r)  X  0.82  =  3.12 

August  '03 2.87  (2.62  +  0.25  r)  X  0.82  =  2.74 

September  '03 3.54  (1.63  +  0.20  r)  X  0.82  =  1.92 

October  '03 3.92  (0.88  +  0.12  r)  X  0.82  =  1.11 

November  '03 0.96  (0.66  +  0.10  r)  X  0.82  =  0.62 

December  '03 4.28  (0.42  +  0.10  r)  X  0.82  =  0.69 

Having  found  the  monthly  evaporation,  it  is  evident  that  the  excess 
of  precipitation  over  evaporation  represents  the  run-off;  but  an  exami- 
nation of  these  two  reveals  the  fact  that  during  July  evaporation  exceeds 
precipitation;  this  generally  will  be  the  case  during  several  months  and 
apparently  there  would  be  no  run-off  under  such  conditions.  This,  how- 
ever, is  not  so,  at  least  only  rarely  on  western  streams,  which  sometimes 
dry  up  entirely  during  seasons  of  drought;  but  there  is  water  stored 
in  the  ground  and  in  lakes  and  swamps,  and  whenever  the  evapo- 
ration is  greater  than  precipitation,  and  in  fact  when  the  excess  of 
precipitation  becomes  small,  water  stored  in  the  ground  feeds  out  into 
the  stream. 

It  would  be  well,  at  this  stage,  for  the  reader  to  retrace  his  steps 
and  review  the  discussion  of  drainage  area,  its  topography,  geology, 
flora,  and  culture,  as  the  important  influences  of  all  of  these  conditions 
are  about  to  become  more  apparent. 

The  supply  from  which  a  stream  is  fed  during  periods  when  precipi- 
tation only  slightly  exceeds  evaporation,  or  when  there  is  no  such  excess, 
which  is  the  case  on  almost  every  system  during  the  growing  season 
from  June  to  September,  depends  on  the  drainage  area  characteristics: 
if  the  ground  contains  no  storage,  there  can  be  no  supply ;  if  the  storage 
is.  large,  the  supply  from  it  will  be  correspondingly  plentiful,  yielding 
frequently  as  much,  and  a  greater  flow  than  a  normal  rainfall  would 
furnish.  The  rainfall  is  generally  very  small  during  two  or  three 
months  of  this  growing  season:  a  wet  summer  is  an  exception  rather 
than  the  rule. 

From  a  generalization  of  drainage  area  characteristics,  as  repre- 
sented by  topography  and  geology,  the  investigations  in  this  field  have 


THE   SURVEY  ill 

resulted  in  a  classification  of 

(1)  An  area  of  bold  relief  and  in  highlands  with  no  surface  storage. 

(2)  An  area  of  drift-covered  rock  with  no  surface  storage. 

(3)  An  area  of  deep  drift  and  large  surface  storage. 

Others  could  be  added  as  being  descriptive  of  conditions  between  these, 
but  in  practice  the  investigator  will  generally  find  that  the  area  under 
examination  is  practically  described  by  one  of  these  three  classes.  It  is 
evident  that  the  ground  storage  capacity  of  these  three  will  greatly  differ, 
and,  as  they  do,  they  will  be  capable  of  furnishing  a  comparative  supply 
to  the  stream  during  the  periods  of  small  rainfall. 

In  the  course  of  the  search  for  a  practical  determination,  fixed  values 
of  ground  flow  from  areas  of  these  different  classes  have  been  found  and 
are  represented  by  ground-flow  diagrams  on  Profile  2.  The  side  nota- 
tions stand  for  monthly  flow  in  inches  from  the  ground  storage,  while 
those  at  the  bottom  represent  the  corresponding  depletion  of  the  ground 
storage,  also  in  inches.  Examining  the  projected  curves,  their  more  gradual 
flattening  will  be  noted  as  the  storage  capacity  of  the  area  increases, 
while  all  finally  assume  almost  the  horizontal,  indicating  that  storage  is 
nearly  depleted;  it  will  also  be  seen  that  each  of  these  begins  to  feed  out 
with  a  flow  of  two  inches,  which  means  that,  whenever  the  excess  of 
precipitation  over  evaporation  is  less  than  two  inches,  ground  storage 
begins  to  supply  in  accordance  with  the  quantity  of  the  remaining  stor- 
age. The  essence  of  all  of  this  ground  storage  topic  may  be  expressed 
by  the  following: 

The  ground  storage  conserves  the  excess  precipitation  and  from  it  feeds 
to  the  stream  during  dry  seasons  in  accordance  with  its  capacity. 

We  may  now  go  back  to  the  finding  of  the  flow  on  the  Maitland 
River,  and  we  note  that  during  the  very  first  month  the  excess  of  precipi- 
tation over  evaporation  is  less  than  two  inches,  and,  from  what  has  been 
said  before,  we  know  that  ground  storage  will  add  some  supply  and  the 
storage  itself  will  be  correspondingly  depleted.  The  ground-flow  diagram 
arrangement  shows  what  the  depletion  corresponding  to  a  certain  out- 
flow from  ground  storage  is,  which  may  be  expressed  as  dt  =  depletion 
or  condition  at  the  end  of  the  month  preceding  the  one  under  consider- 
ation, when  d2  for  present  month  =  dt  +  e  +  f  —  r,  being  the  sum  of  existing 
depletion  and  present  month's  evaporation  and  flow  less  precipitation, 


112  HYDRO-ELECTRIC   PRACTICE 

and  for  the  average  condition  of  the  month 


. 


Applying  this  to  December,  1902,  where 

r  -  2.18,  and  e  =  0.52,  ^~  =  0.83, 

£ 

there  being  no  previous  depletion,  therefore  dt  =  0  and 

d  =  |-  -  0.83. 

Zi 

The  ground-flow  diagram  for  Maitland  River  is  that  of  a  drainage 
area  with  drift-covered  rock  and  no  surface  storage  (No.  2)  ,  and,  exam- 
ining the  curve,  we  find  that  the  intersection  of  d  =  0.25  and  f  =  2.15 
fills  the  condition  because  |  =  1.07  and  {  -  0.83  =  0.24;  "f  "  is  there- 
fore 2.15  inches.  The  difference  between  the  sum  of  evaporation  and  flow 
and  of  precipitation  must  come  from  ground  storage  and  d  =  e  +  f  —  r, 

or  in  this  case 

0.52  +  2.15  -  2.18  =  0.49. 

When  the  next  month,  January,  1903,  is  examined,  r  =  1.36,  e  = 
0.33,  and  ground  storage  is  depleted  by  0.49  inch. 

Then  from  A       f        i        r  -  e 

=  2  "   dl  "    ~2~ 

=  |  +  0.49  -  0.52 
Ji 

-1-0.03, 

which  is  practically  met  by  the  intersection  on  the  ground-flow  diagram 
of  0.78  d  and  1.62  f  or  0.78  =  0.81-0.03,  and  f  therefore  =1.62,  while 
depletion  is  again  =  to  total  evaporation  and  flow  less  total  precipita- 


f 

Profile  2 
Groundflow  diagrams 

2.0  v 

\ 

C 

~\ 

i  *         V- 

1.5           5 

V 

^ 

Bold  relief  and  in 

1  ft   -               -    ^    • 

l.O                             v 

Highlands 

s 

s~ 

_  _                                                 v  a 

v.5 

^««^ 



—  —  —  

ft 

in           q           in 

o           o           «-«           -* 

2ej 

q           tn           q           in           o 
ri            ri            rt            ro            ^ 

in     j 

\ 

^ 

*)  ft     •       \ 

Z.U                          \^ 

k 

V 

^ 

1      S                                                   ^^ 

_ 

1.9                                                N 

and  no  swamp 

*  r 

*> 

storage 

>  i 

i  n  -                       -  v^^- 

--»  . 

=  ~-  --._.  „____ 

~~  -  -  .  _ 

t\  E      - 

*  ""  i 

U.5 

"  *  •  , 

-_         --                                      -                                        ~~-= 

-c 

i)       in        Of       in       © 

mom        q        in        q        in        q 

U>    j      < 

O               ^H              ^H               <S 

2e 

ri       rn       w        ^'       ^'       in       in       \d 

SO    a     t 

|      | 

1  " 

\ 

\ 

-  f.           Jj  " 

Sandy  Watershed 

v 

'v 

with 

•>  N 

_  *  J 

5*»  ^ 

~   ~  "       large  swamp  storage 

11  •-  .  „ 

"  *  5  Z 

5  v 

1ft    - 

S 

*  s 

s  x 

_  S  J 

s  V 

n  %  - 

x^ 

Sj 

"  •  t 

"••••  - 

r..  E^l^rtr 

n  - 

From  report  of  Geol.  Survey  of  N.  J.   1894  by  C.  C.  Vermuele  C.  E. 


113 


114 


HYDRO-ELECTRIC   PRACTICE 


tion  =  0.85  +  3.76  -  3.54  =  1.07;  or,  in  other  words,  the  total  supply 
represented  by  the  total  precipitation  and  the  ground  storage  outflow 
(depletion)  must  always  equal  the  total  amount  expended,  that  is  total 
evaporation  and  total  flow.  As  rainfall  increases,  ground  storage  again 
becomes  gradually  replenished,  as  appears  at  the  end  of  the  year.  In 
this  manner  month  by  month  is  taken  up  and  the  run-off  found  in 
inches  from  the  drainage  area,  which,  for  practical  application,  is  later 
transposed  into  flow  of  cubic  second  feet. 

The  convenient  arrangement  of  these  deductions  is  as  follows: 

Column  1  gives  the  months,  commencing  with  December  of  the 
previous  year,  because  the  accepted  water  year  is  from 
December  to  November. 

Column  2  shows  monthly  precipitation r 

Column  3  shows  total  precipitation R 

Column  4  shows  monthly  evaporation e 

Column  5  shows  total  evaporation E 

Column  6  shows  monthly  run-off f 

Column  7  shows  total  run-off F 

Column  8  shows  depletion  of  ground  storage d 

The  computations  are  here  given  in  detail  in  accordance  with  above 
arrangement,  and  Column  6  contains  the  resultant  monthly  run-off  in 
inches  per  square  mile  of  drainage  area. 

ORDINARY  DRY  YEAR  MONTHLY  RUN-OFF  FROM  MAITLAND,  ONT.,  RIVER 
WATER-SHED.     (All  measurements  in  inches.) 


1903 
Month. 
1 

December  '02  .... 

PRECIP 
Monthly. 
2 
2.18 

ITATION  : 

Total. 
3 

2.18 
3.54 
5.34 
6.53 
7.42 
10.16 
13.01 
15.69 
18.56 
22.10 
26.02 
26.98 
31.26 

EVAPORATION  : 
Monthly.        Total. 
4                    5 

0.51          0.51 
0.33          0.84 
0.39          1.23 
0.48          1.71 
0.77          2.48 
1.93          4.41 
2.56          6.97 
3.04        10.01 
2.67         12.68 
1.87         14.55 
1.08         15.63 
0.54         16.17 
0.68         16.85 

RUN-OFF  : 
Monthly.        Total. 
6                   7 

1.67          1.67 
1.03           2.70 
1.41           4.11 
1.44           5.55 
0.76           6.31 
0.60           6.91 
0.60           7.51 
0.40          7.91 
0.33           8.24 
0.44           8.68 
1.71         10.39 
1.32         11.71 
2.70         14.41 

Ground 
Storage. 
8 

full 
full 
full 
—0.73 
1.37 
1.16 
1.47 
2.23 
2.36 
1.13 
full 
0.90 
full 

Remarks. 

T  =  46° 

Ground  flow 
taken  as 
from  watershed 
of  bold  relief 
with  no 
swamp  or  lake 
storage  and 
some  drift 
overlying 
rock. 

January  '03  

1.36 

February  '03  

1.80 

March  '03  

1.19 

April  '03  

.     089 

May  '03  

2  74 

June  '03  

.  .  .   2.85 

July  '03  

.  .     2  68 

August  '03  

...   2  87 

September  '03  

.  .  .  3.54 

October  '03  

.  .  .   3.92 

November  '03  

.  .  .  0.96 

December  '03  .  . 

.   4.28 

THE   SURVEY  115 

ARTICLE  46. — Reservoir  sites  should  be  looked  for  along  the  tribu- 
taries above  the  power  site,  and  on  lakes  or  swamps  in  the  drainage  area, 
and  when  found  they  should  be  surveyed  to  determine  their  available 
area  and  depth,  location  of  reservoir  dams,  and  cross-section  at  such. 

Diagram  4  gives  the  continuous  flow  capacity,  for  various  periods 
of  time,  in  cubic-second  feet,  from  an  area  of  one  hundred  acres  and  one 
foot  depth,  from  which  the  area  corresponding  to  a  required  flow,  or 
vice  versa,  can  be  taken. 

Evaporation  from  reservoir  surface,  as  per  Table  4,  Article  14,  must 
not  be  overlooked,  and  some  allowance  should  be  made  for  water  escap- 
ing from  storage  by  seepage  and  by  leakage  through  reservoir  dam.  The 
time  required  by  the  flow,  from  the  storage  reservoir  to  the  power  site, 
must  also  be  determined. 

ARTICLE  47. — The  prevalence  of  timber  floating  down  the  stream, 
either  from  logging  operations  or  trees  on  the  banks  which  will  be  up- 
rooted by  the  raising  of  the  water  above  the  dam,  should  be  investigated  ; 
also  the  ice  conditions  during  the  winter  periods,  to  what  thickness  it  is 
likely  to  form  and  whether  there  is  likelihood  of  its  gorging  in  the  river 
bends  or  above  islands. 


CHAPTER  VII 

DEVELOPMENT    PROGRAMME 

THE  data  collected  by  the  various  operations  described  in  Chapter 
VI.  will  furnish  the  information  required  to  plan  the  best  programme. 
ARTICLE  48. — The  direct  development  utilizes  all  the  available  fall 
at  the  dam,  and  the  power  station  is  located  at  its  end  or  in  the  in- 
terior of  the  spillway.  This  plan  is  recommended  because  of  the  con- 
centration of  the  entire  plant  at  one  point  and  the  consequential  saving 
in  the  operation  cost,  and  because  of  its  securing  the  highest  obtainable 
hydraulic  efficiency  of  the  power  components,  fall  and  flow;  by  any 
other  programme  losses  of  both  of  these  are  incurred.  Any  diversion 
sacrifices  a  portion  of  the  available  fall  by  the  slope  in  canals  and  flumes 
or  the  friction-head  in  pipe  lines,  while  losses  of  flow  are  represented  by 
leakage,  evaporation,  and  ice  conditions.  When  the  water  is  passed  at 
once  from  the  upper  pool  through  the  turbines,  no  such  losses  occur. 
The  conditions  which  determine  this  choice  are  the  cost  of  the  dam  and 
embankments  as  compared  with  that  of  a  lower  dam  and  of  diversion 
works ;  also  the  extent  and  cost  of  flowage  for  the  upper  pool  and  further 
the  advantages  secured  by  an  extensive  pond  area;  the  flood  flow  condi- 
tions as  affecting  power  house ;  the  rise  in  the  lower  pool  and  the  fluctua- 
tions in  the  working  head.  The  rapid  increase  of  cost  with  the  height 
of  the  dam  is  shown  on  Diagrams  9  and  10,  Art.  23,  and  of  the  foundations, 
if  in  alluvial  location,  and  of  abutments,  on  Diagram  11,  Art.  23.  When 
the  location  is  in  a  narrow  rock  gorge,  the  entire  width  of  the  river  will 
be  required  for  the  passage  of  the  flood  flow,  and  then  it  is  not  permissible 
to  occupy  any  portion  of  it  by  the  power  house;  to  create  a  location  for 
it  in  the  rock  bluff  would  be  a  costly  undertaking.  The  solution  for  such 
a  case  may  be  found  in  arranging  the  interior  of  the  spillway  for  the 
power  station,  as  will  be  detailed  further  on,  and  in  this  way  a  spillway 
of  the  full  river  width  becomes  available  and  the  direct  development 
feasible.  If  the  river  is  subject  to  frequent  high  stages,  when  the  discharge 
over  the  spillway  represents  large  volumes,  it  will  correspondingly  raise 
the  level  in  the  power-house  pits  and  may  impede  the  efficiencies  of 
turbines;  floating  timber  and  ice  also  have  a  bearing  upon  this  pro- 
ne 


DEVELOPMENT   PROGRAMME  117 

gramme,  as  it  may  necessitate  costly  safeguards  to  prevent  injury  to  the 
power  house  or  interference  with  the  free  entrance  of  the  water  to  the 
turbine  chambers.  Thus,  while  the  direct  development  plan  realizes  the 
highest  percentage  of  flow  and  fall  and  represents  the  greatest  simplicity 
of  works  and  lowest  operating  charges,  and  therefore,  as  a  rule,  the  most 
economical,  the  conditions  may  sometimes  be  such  that  its  adoption  is 
prohibited  by  the  first  cost  or  by  considerations  of  safety  and  of  con- 
tinuity of  operations. 

ARTICLE  49. — The  short  diversion  programme  meets  conditions  where 
the  dam  location  of  the  power  house  is  not  feasible  because  of  contraction 
of  the  river  channel  or  of  the  insufficient  height  of  the  spillway  to  accom- 
modate the  power  equipment  in  its  interior.  The  power  house  is  then 
located  as  close  below  the  dam  as  practicable,  but  at  a  safe  distance 
from  the  spillway  overfall.  Water  is  conducted  from  the  spillway  pond 
in  accordance  with  the  volume  to  be  utilized,  in  a  canal,  flume,  or  pipe. 
Since  this  programme  is  adopted  only  to  escape  the  excessive  cost  or 
dangerous  conditions,  it  presents  more  problems  requiring  careful  solu- 
tion than  the  former.  No  matter  how  short  the  diversion  works,  proper 
guards  at  point  of  intake  are  required,  which,  in  combination  with  the 
spillway  structure,  cover  a  wide  range  of  types.  It  may  be  advisable  to 
locate  the  intake  at  some  distance  above  the  dam,  in  order  to  escape 
heavy  rock  cutting  or  ice  gorges  and  to  secure  the  most  complete  diver- 
sion of  the  low  flow  into  it;  to  accomplish  the  latter  object,  on  a  wide 
river  it  may  be  necessary  to  provide  a  diverting  dike  or  weir.  When  the 
rock  bank  continues  precipitous  for  some  distance  above  the  dam,  a 
partition  wall  may  be  required,  or  in  some  such  cases  it  may  be  found  to 
be  most  economical  to  arrange  for  diversion  through  a  tunnel  around  the 
dam  abutment.  The  intake  entrance  must  be  guarded  by  some  kind  of 
head  gates,  their  character  depending  upon  a  number  of  controlling 
conditions  which  will  be  treated  in  detail  later  on.  The  diversion  method 
will  be  shaped  by  the  character  and  the  formation  of  the  river  bank  and 
the  volume  to  be  carried,  detail  considerations  of  which  will  be  found 
under  "Canals,  Flumes,  and  Pipe  Lines."  The  power  house  is  placed 
at  the  most  convenient  point  immediately  below  the  dam;  types  will 
be  described  in  the  next  chapter. 

ARTICLE  50. — The  distant  diversion  programme  is  applicable  only 
when  the  concentration  of  the  available  fall  at  one  point  is  not  feasible 
or  is  too  costly.  The  spillway  or  reservoir  dam  is  located  at  the  most 


118 


HYDRO-ELECTRIC   PRACTICE 


DEVELOPMENT  PROGRAMME 


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DEVELOPMENT   PROGRAMME  121 

advantageous  point,  and  the  water  is  conducted  from  there  to  the  lower 
level  by  a  canal,  flume,  or  pipe  line,  and  the  power  station  is  at  the 
terminal.  The  features  of  this  class  are  very  similar  to  those  of  the  short 
diversion  programme,  the  difference  being  only  the  distance  of  diversion. 

The  choice  of  development  programme  is,  as  a  rule,  not  a  difficult 
problem;  as  the  existing  conditions  in  most  cases  readily  point  to  one 
or  the  other,  only  occasionally  may  some  doubt  exist  as  between  the 
first  two. 

When  the  development  is  on  the  lower  reach  of  a  river  without  falls 
or  rapids,  aiming  to  concentrate  so  much  of  its  natural  fall  as  may  be 
feasible  with  the  available  height  of  its  banks,  and  when  the  formation 
is  generally  alluvial,  the  direct  programme  is  the  solution,  the  power 
house  being  placed  at  the  end  of  the  spillway,  as  is  shown  on  Plan  8, 
of  the  Mottville,  Mich.,  development;  or  if  this  is  30  feet  and  higher,  in 
the  spillway's  interior,  as  illustrated  on  Plan  9,  of  the  Manistee  River, 
Mich.,  plant.  On  such  locations  high  flood  conditions  may  advise  the 
adoption  of  the  second  programme,  or  the  peculiar  formation  shown  in 
Plan  10,  High  Bridge,  Mich.,  where  a  promontory  juts  out  into  the  river, 
presents  a  favorable  condition  for  the  short  diversion  development.  The 
third  would  be  available  only  in  case  sufficient  more  fall  could  be  secured 
by  it,  for  instance  when  the  river  makes  a  long  detour,  doubling  back  to 
within  a  short  distance  abreast  of  the  dam  site,  the  diversion  location 
being  across  the  peninsula  formed  by  the  river's  oxbow  course.  The  fall 
of  rivers  of  such  characteristics  rarely  exceeds  two  feet  per  mile  and  the 
length  of  its  course  around  the  detour  must  be  five  miles  or  more  to  war- 
rant such  a  programme;  in  fact,  its  advisability  must  be  weighed  by  a 
comparison  of  the  earning  capacity  of  the  fall  thus  gained  and  the  invest- 
ment represented  by  the. cost  of  the  diversion  works  plus  their  mainten- 
ance and  operation.  This  case  is  illustrated  on  Plan  11,  of  the  Clinton 
River,  Mich.,  Renshaw  site  development,  where  the  stream  departs 
easterly  for  a  distance  of  five  miles  and  returning  approaches  the  dam 
site  within  1200  feet,  gaining  12  feet  fall. 

In  rivers  with  rock  beds  and  palisade  banks  the  first  programme  is 
admissible  only  when  the  spillway's  interior  can  be  utilized  for  the  power 
station,  as  the  entire  width  of  the  river  channel  must  remain  available, 
unobstructed,  for  the  passage  of  the  flood  flow,  and  the  creating  of  a 
power-house  site  at  the  spillway  end  involves  the  removal  of  rock  and 
would  be  very  costly.  Such  a  development  is  shown  on  Plan  12,  of  the 


122 


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Canon  Falls,  Minn.,  plant,  the  river  forming  practically  a  rock  gorge, 
the  spillway  40  feet  high,  and  the  power  station  inside  of  it;  this  can  be 
carried  out  only  when  the  spillway  is  25  feet  or  higher,  and  the  only  alter- 
native is  as  shown  in  Plan  13,  at  Little  Hickman,  Green  River,  Ky.,  where 
the  power  house  is  200  feet  below  the  dam,  diversion  in  this  case  being 
by  tunnel. 

When  falls  or  rapids  continue  over  a  considerable  distance,  the  third 
programme  only  is  available, — that  is,  if  a  fall  exceeding  the  feasible 
accumulation  at  one  point  is  to  be  utilized.  Plan  24,  of  the  Pennington, 
Ind.  Ter.,  illustrates  this,  the  fall  in  3J  miles  being  135  feet;  diversion  is  by 
flume  and  pipe  line;  also  Plan  15,  of  the  development  at  Sault  Ste.  Marie, 
Mich.  The  development  of  most  of  the  high  falls  is  of  this  type,  as 
appears  on  Plan  16,  of  the  Eugenia  Falls,  Ont.,  where  a  vertical  drop  of 
78  feet  is  followed  by  continuous  rapids  in  the  stream  flowing  for  one 
mile  around  a  rock  bluff;  the  spillway  here  is  placed  above  the  fall,  and 
|  mile  diversion  by  tunnel  and  pipe  line  terminates  at  a  point  400  feet 
below  the  spillway  crest.  Occasionally  successive  falls  can  only  be  de- 
veloped by  separate  treatment, — that  is,  topography  or  right-of-way  lim- 
itations prohibit  any  diversion  programme.  This  is  the  case  on  the 
Sandusky  River  near  Fremont,  0.,  Plan  17,  where  a  fall  of  40  feet  occur- 
ring in  half  a  mile  can  be  developed  only  by  two  separate  dams  within 
a  quarter  of  a  mile  of  each  other.  Only  the  best  market  conditions  will 
warrant  such  a  treatment  when  the  operating  cost  of  the  two  stations 
creates  a  heavy  charge  against  the  enterprise. 

ARTICLE  51. — Development  scope — i.e.,  what  output  capacity  is  the 
development  to  be  based  upon — should  be  determined  before  the  plant 
is  designed.  This  question  is  be  decided  from  the  considerations  of 
the  available  market  for  the  product  and  of  the  fall  and  flow  which  can 
be  utilized.  The  market  topic  has  been  discussed  in  Part  I.  In  the 
direct  development  it  is  generally  advisable  to  utilize  all  the  available 
fall ;  with  distant  diversion  the  cost  of  the  latter  corresponding  to  the 
fall  gained  is  the  criterion.  If  only  a  part  of  the  available  power  is  to  be 
developed,  the  decision  whether  to  use  partial  fall  or  flow  rests  with  the 
cost  of  works  adapted  to  one  or  other  purpose;  this,  however,  is  rarely 
the  case ;  on  the  contrary,  it  will  be  almost  uniformly  desirable  to  develop 
the  largest  possible  capacity,  as  the  market  for  the  product  is  sooner  or 
later  created,  and  the  greater  the  output  at  a  given  site  the  more  econom- 
ical will  be  the  unit  development  and  the  operating  cost.  An  estimate 

9 


130  HYDRO-ELECTRIC   PRACTICE 

of  the  largest  practicable  development  is  among  the  first  questions  met 
while  the  project  is  being  exploited,  and  when  it  is  furnished  it  must  be 
based  upon  reliable  data  and  be  conclusive. 

The  low  flow  during  the  nine-month  period  will  in  the  majority  of 
cases  be  the  most  recommendable  to  adopt  as  the  power  flow;  that 
during  the  remaining  period  of  three  months  lower  flow  'must  be 
increased  by  drawing  supply  from  reservoir  storage,  by  ponding  during 
non-operating  hours,  by  auxiliary  power  plant,  or  by  charging  an  electric 
storage  battery  with  so  much  of  the  current  output  as  is  not  called 
for  because  of  the  fluctuations  of  connected  loads. 

It  is  only  in  rare  cases  that  the  available  market  exceeds  the  low- 
flow  output  from  the  very  beginning;  if  such  is  the  case,  the  cost  of 
creating  any  or  all  of  these  supplementary  flow  or  power  sources  must 
be  provided  for  in  the  first  development  estimate;  if,  however,  none 
such  will  be  required  at  the  outset,  the  future  increase  of  power  demand 
will  take  care  of  the  added  investment  for  these  additional  power  sources. 


CHAPTER    VIII 

STRUCTURAL   TYPES 

IN  this  chapter  are  presented  some  practical  designs  for  the  works 
of  a  hydro-electric  plant.  They  are  preceded  by  the  nomenclature  of 
terms  herein  employed,  specifications  of  material  and  of  methods,  fol- 
lowed by  the  development  of  one  or  more  designs  for  each  separate 
structure  of  importance,  with  an  outline  of  the  theory  of  stability  and 
adaptability  from  which  they  are  evolved,  and  concluded  with  estimates 
of  quantities  and,  in  some  cases,  of  cost.  This  treatment  of  structural 
types  is  largely  as  developed  in  the  author's  practice  and  as  proved 
practical,  safe,  and  economical  for  the  purpose. 

The  dam  comprises  the  entire  structure  by  which  the  river  and  its 
valley  are  closed,  from  bank  to  bank,  for  the  purpose  of  accumulating 
the  water,  concentrating  its  fall  at  one  fixed  point,  and  diverting  the 
flow  in  the  desired  direction.  The  dam  may  or  may  not  pass  water  over 
its  crest;  in  the  affirmative  case  it  becomes  a  spillway,  in  the  other  a 
reservoir  dam;  generally  it  is  a  composite  structure  of  both  types,  the 
river  proper  being  closed  by  the  spillway,  which  terminates  in  abut- 
ments and  is  flanked  at  one  or  both  ends  by  reservoir  embankments  or 
bulkheads. 

The  spillway  consists  of  the  foundation  and  superstructure. 

ARTICLE  52. — The  foundation's  functions  are  to  prevent  the  passage 
of  water  below  the  structure  and  to  afford  rigidity  of  position  to  the 
superstructure.  Its  design  is  determined  by  the  character  of  the  material 
at  its  site,  as  to  hardness,  strength,  and  porosity,  the  height  and  weight 
of  the  superstructure,  the  maximum  height  of  water  to  be  ponded,  and 
the  effect  of  its  overflow. 

Foundation  sites  are  in  rock  or  alluvial  formation. 

The  primitive  rocks,  formed  by  original  solidification,  fusion,  or 
later  volcanic  action,  are  granite  and  sienite;  they  are  igneous  and 
silicious.  Granite  is  composed  of  quartz,  feldspar,  and  mica,  with  talc 
and  hornblende  as  impurities;  its  hardness  and  durability  are  increased 
by  the  proportion  of  contained  quartz  and  decreased  by  that  of  feld- 
spar and  mica;  it  is  unstratified.  Sienite  closely  resembles  granite;  it 

131 


132  HYDRO-ELECTRIC    PRACTICE 

consists  of  feldspar  and  hornblende  with  some  quartz  and  mica;  it  is  as 
hard  and  durable  as  granite. 

The  transition  or  metamorphic  rocks  are  gneiss,  sienite  gneiss,  green- 
stone, trap,  and  basalt;  they  are  sedimentary,  but  have  undergone 
changes  due  to  heat,  pressure,  or  chemical  action.  Gneiss  or  mica  slate 
is  silicious  and  stratified,  resembling  granite.  Sienite  gneiss  is  a  stratified 
sienite.  Greenstone,  trap,  and  basalt  consist  of  hornblende  and  feldspar 
and  are  unstratified. 

The  secondary  rocks  are  the  sandstones,  which  are  formed  by  the 
solidification  of  disintegrated  primitive  rocks,  being  composed  of  grains 
of  silicious  rocks  cemented  together  by  silica,  lime,  and  alumina.  To 
this  class  also  belongs  soapstone,  silicate  of  magnesia.  The  physical 
characteristics  of  sandstone  vary  with  its  density  and  it  is  generally 
stratified. 

The  tertiary  rocks  are  calcareous,  being  formed  of  shells  and  marine 
animals  compacted  under  pressure  of  superimposed  rock  or  soil;  to  this 
class  belong  the  limestones,  marble,  chalk,  and  slates.  Limestone,  car- 
bonate of  lime,  varies  from  the  hardness  and  density  of  marble  to  the 
softness  and  porosity  of  chalk.  Slate  occurs  in  thin  strata,  of  which  clay 
forms  the  basis. 

PHYSICAL  CHARACTERISTICS  OF  ROCKS. 


Rock. 
Granite                            , 

Weight  per    * 
Cubic  Foot. 
180  Ibs. 

Crushing  Strength         Stratified  or 
per  Square  Foot.                   not. 

750  tons             Unstratified 
750  tons             Unstratified 
700  tons             Unstratified 
700  tons             Unstratified 
700  tons             Unstratified 
700  tons             Unstratified 
700  tons             Unstratified 
600  tons            Stratified 
500  tons             Unstratified 
500  tons             Unstratified 
600  tons             Stratified 

Sienite                    

180  Ibs. 

Gneiss 

180  Ibs. 

Sienite  gneiss                            .  .  . 

180  Ibs. 

Trap                       

180  Ibs. 

Basalt 

180  Ibs. 

Greenstone                              

180  Ibs. 

Sandstone                         

150  Ibs.' 

Marble 

168  Ibs. 

Limestone  (hard)                

168  Ibs. 

Slate.  . 

.    175  Ibs. 

Under  alluvials  are  comprised  gravel,  sand,  clay,  loam,  marl,  and  peat. 

Gravel  is  fragmentary  rock  reduced  by  the  atmosphere  and  water  to 
pebbles,  chiefly  of  quartz  and  of  crystalline  origin.  Sand  is  of  the  same 
origin  as  gravel  and  consists  merely  of  smaller  particles,  generally  inter- 

*  For  structural  considerations  0.25  only  of  crushing  strength  here  given  should  be  accepted  for 
safe  load  capacity. 


STRUCTURAL   TYPES 


133 


mixed  with  gravel;  it  is  of  angular  or  rounded  fragments  as  its  existence 
is  due  to  recent  or  older  disintegration  of  the  rocks.  Quicksand  consists 
of  small  rounded  particles  of  calcareous  materials  which,  under  the 
influence  of  water,  becomes  like  a  fluid. 

Clay  is  decomposed  crystalline  rock,  consisting  of  hydrated  silica 
or  alumina,  and  generally  contains  some  sand  and  lime;  it  occurs  in  all 
colors  from  lightest  to  darkest,  and,  according  to  quantity  of  water 
contained  in  it,  is  soft  or  stiff.  Loam  is  a  mixture  of  clay  and  sand,  the 
latter  predominating  so  far  that  the  clay  loses  its  coherence.  Soil  is  fine 
earthy  material  mixed  with  more  or  less  organic  matter;  mud  is  moist, 
soft  soil;  silt  is  a  fine  earthy  sediment. 

Marl  is  correctly  classed  as  a  tertiary  formation,  and  is  a  consoli- 
dated mixture  of  clay  and  carbonate  of  lime  which  readily  disintegrates 
when  exposed  to  the  atmosphere. 

Peat  is  decomposed  vegetable  matter,  spongy  and  containing  much 
water  near  the  surface. 


Material. 


PHYSICAL  CHARACTERISTICS  OF  ALLUVIALS. 


*  Weight  per 
Cubic  Foot. 


Gravel 90-106  Ibs. 

Sand,  dry  and  loose 90-106  Ibs. 

Sand,  wet ; 118-129  Ibs. 

Clay,  dry , 119      Ibs. 

Clay,  in  lumps 63      Ibs. 

Clay,  damp 

Clay,  wet 

Loam,  dry,  loose 72-80    Ibs. 

Loam,  wet 66-68    Ibs. 

Mud 104-110  Ibs. 

Gravel  and  loam 

Gravel  and  sand,  dry 

Loam  on  moist  clay 

Loam  on  wet  clay 

Clay  on  gravel 

Peat.., 


t  Bearinc-  per 

Angle  of 

Coefficient 

Square 

Foot. 

Repose. 

of  Friction. 

2-3 

tons 

38° 

0.78 

2-3 

tons 

28° 

0.53 

2-3 

tons 

28°' 

0.53 

4-6 

tons 

4-6 

tons 

45° 

4-6 

tons 

45° 

1.0 

4-6 

tons 

15° 

0.27 

4-6 

tons 

35° 

0.70 

4-6 

tons 

35° 

0.70 

4r6 

tons 

zero 

0.70 

2-3 

tons 

38° 

0.78 

8-10  tons 


45° 
45° 
17° 
45° 
20° 


1.0 
1.0 
0.3 
1.0 
0.36 


Having  analyzed  the  character  of  the  material  at  the  foundation 
site,  the  following  arguments  and  deductions  should  control  the  design. 

In  rock  its  hardness,  stratification,  condition  and  shape  of  surface 
determine  the  foundation. 


*  Compacted,     f  At  depth  beyond  atmospheric  influence. 


134  HYDRO-ELECTRIC    PRACTICE 

In  hard  unstratified  rock  with  level  surface  no  foundation  is  required; 
the  homogeneous  ledge  will  not  permit  water  to  pass  beneath  its  surface 
and  it  will  safely  carry  the  superstructure  which  is  anchored  and  keyed 
to  it. 

In  hard  but  stratified  rock  a  cut-off  wall  must  be  constructed  along 
the  upstream  side  of  the  spillway  structure  in  a  trench  excavated  from 
the  rock  to  a  sufficient  depth  to  pass  below  those  strata  which  are  less 
than  two  feet  thick,  its  upper  portion  becoming  part  of  the  superstruc- 
ture. The  rock  ledge  may  be  of  sufficient  solidity  to  carry  safely  the 
spillway. 

In  soft  stratified  rock  a  cut-off  wall  is  essential.  The  superstructure 
may  be  founded  on  the  rock  surface  after  the  soft,  disintegrated  upper 
portions  are  completely  removed,  but  an  apron  must  be  constructed  on 
the  downstream  side  of  the  superstructure  to  receive  the  overfall  and 
resist  its  erosive  force. 

In  compact  alluvial  gravel  and  sand,  defined  as  hardpan,  with  no 
interior  sand  strata  to  a  depth  of  one-third  of  the  water  height  on  the 
upstream  side  of  the  spillway,  a  cut-off  toall  is  required  to  a  depth  below 
the  river  bed  equal  to  one-fourth  of  the  maximum  water  head;  when 
the  aggregate  weight  of  the  superstructure  and  water  does  not  exceed 
two  tons  per  square  foot  of  its  base,  it  may  be  placed  directly  upon  the 
levelled,  cleaned  hardpan  surface,  but  when  the  load  exceeds  this  limit, 
bearing  piles  must  be  driven  to  support  safely  the  superstructure,  which 
may  be  placed  directly  upon  them,  or  a  concrete  foundation  floor  may 
be  laid,  the  pile  tops  being  imbedded  in  it.  An  apron  is  required  on  the 
downstream  side. 

In  clay  with  no  sand  strata  or  pockets  for  a  depth  of  one-fourth  of 
the  maximum  water  head,  upstream  cut-off  walls  must  be  constructed 
to  a  depth  of  one-third  of  the  maximum  water  head,  and  these  must  form 
a  part  of  the  foundation  floor,  which  rests  upon  the  bearing  piles  and  is 
extended  up-  and  downstream  of  the  superstructure  base  as  aprons. 

In  soft  alluvials  of  clay,  gravel,  sand,  loam,  silt,  or  peat,  upstream 
cut-off  walls  are  required  to  a  depth  penetrating  into  impermeable 
material  or  to  rock,  and  a  pile  bearing  foundation  with  up-  and  down- 
stream aprons,  as  will  be  later  on  described,  must  be  constructed. 

In  all  alluvial  locations  the  foundation  must  be  specially  designed 
to  provide  safety  against  scour  or  underwashing  and  secure  ample  bearing 
capacity.  Whenever  sand  strata  exist,  even  at  a  considerable  depth,  at 


STRUCTURAL   TYPES 


135 


the  spillway  site  or  upstream  of  it,  they  may  rise  or  connect  with  higher 
strata  of  the  same  material,  and  eventually  form  channels  through  which 
the  water,  under  increased  pressure  head,  finds  a  passage  beneath  the 
spillway  base,  which  will  cause  leaks  and  in  time  remove  some  of  the  mass 
upon  which  the  structure  rests.  The  only  reliable  safeguard  under  such 
conditions  lies  in  securely  confining  so  much  of  the  mass  between  the 
cut-off  and  intermediate  foundation  walls  or  beams  that  its  weight 
exceeds  the  sliding  force,  and  to  penetrate  through  and  below  this  body 
with  bearing  piles  which  will  safely  maintain  the  superstructure,  even 
should  it,  so  to  speak,  float  upon  the  mass  enclosed  between  the  cut-off 
and  the  foundation  walls. 
Upon  this  theory  the  depths 
of  the  cut-off  walls  should 
be  based. 

This  liability  of  water 
passing  under  the  foundation 
by  way  of  permeable  strata 
is  not  confined  to  the  river 
bed,  but  in  fact  is  much  more 


likely  to  have  its  origin  in 
the  banks,  where  the  con- 
stant passage  of  the  ground- 
water  into  the  stream  has 
formed  permanent  channels  which,  when  the  water  is  ponded  above 
them,  become  readily  connected  by  lateral  channels;  springs  issuing 
from  the  river  bank  are  evidences  of  the  ground- water  channels,  which, 
however,  are  not  always  thus  plainly  marked.  Of  this  subject  more 
will  be  said  under  "Embankments." 

ARTICLE  53.  Terms,  Materials,  and  Methods.  —  (A)  Coffering  com- 
prises the  operations  and  structures  required  to  control  the  water  during 
construction,  to  exclude  it  from  the  site. 

(B)  Dike,  Fig.  12,  is  a  loosely  thrown  up  rock-and-earth  bank; 
its  function  is  to  exclude  water  from  the  site  it  encloses;  it  consists  of 
a  core  of  loose  rock  of  all  sizes  and  an  earth  or  clay  and  sand  facing  fill. 
Loosely  piled  limestone  and  sandstone  weigh  86  pounds  per  cubic  foot; 
one  cubic  yard  solid  of  either  yields  1.75  of  loose  volume.  A  rock  bank 
with  slopes  of  one-half  in  one,  no  top  width,  and  of  height  equal  to  the 
depth  of  water  in  which  it  is  placed,  is  safe  against  overturning  by  a 


Dike. 


136 


HYDRO-ELECTRIC   PRACTICE 


Timber  Sheet. 


factor  of  two,  and  can  be  made  practically  water-tight  by  placing  alter- 
nate coverings  of  straw,  hay,  or  manure  and  ashes,  clay,  or  coarse  loam 
against  its  pressure  side,  the  water  on  the  opposite  side  being  maintained 

at  a  lower  level  while  the 
facing  is  placed.  The  earth 
fill  should  rise  3  feet  above 
the  top  of  the  rock  core. 

(C)  Timber  sheet,  Fig.  13, 
is  a  vertical  curtain  or  wall, 
consisting  of  planks  driven 
to  overlap,  of  sheet  piles  to 
interlock,  or  of  close-driven 
square  piles  for  the  purpose 
of  coffering;  they  are  effec- 
tive only  to  enclose  small 
areas,  and  must  be  strength- 
ened by  waling,  which  are  timbers  secured  horizontally  to  them  at  differ- 
ent heights,  against  which  inclined  timbers,  securely  footed,  are  strutted. 
With  five  feet  of  pressure  head  against  the  timber  sheet  of  three-inch 
planks,  the  struts  must  be  spaced  five  feet.  Such  a  sheet  is  made 
water-tight  by  canvas  cover- 
ing and  earth  facing.  Tim- 
ber sheets  are  driven  to  a 
depth  equal  to  the  water 
head  against  them  and  rise 
3  feet  above  water  surface. 

(D)  Steel  sheet  consists 
of  driven  interlocking  steel 
shapes,  which  are  rolled  of 
different  sections  from  11  to 
45  pounds  per  foot ;  they  are 
driven  like  timber  sheets,  are 
capable  of  resisting  moderate 

pressure  heads  unsupported,  and  can  be  made  water-tight  by  filling  ashes 
against  their  pressure  side;  they  can  be  pulled  out  and  used  again.  Fig. 
14  shows  some  of  the  sections  now  on  the  market. 

(E)  Log  cribs,  Fig.  15,  are  constructed  of  round  logs  laid  upon  each 
other  in  crib  fashion  of  alternate  longitudinal  and  transverse  streaks,  the 


Fig.  14 


Steel  Piling. 


STRUCTURAL   TYPES 


137 


Log  Crib. 


first  from  five  to  sixteen,  the  second  from  eight  to  twelve  feet  centres; 

the  open  rectangular  spaces  enclosed  by  the  logs  are  the  crib  bays;   the 

logs  are  spiked  to  each  other  at  all  crossings  with  f"  round  18"  wrought- 

iron  drifts  set  in   f"  holes; 

logs  may  be  gained  to  secure 

firmer    connections    and    to 

bring    those    of    the    same 

layer,  or  streak,  to  a  uniform 

level.    Log  cribs  are  used  for 

coffering,  confining  and   di- 
recting   flow,    or    retaining 

banks  and  slopes;  they  may 

be  framed  in  place,  the  second 

streak  being  formed  into  an 

open  log  floor  and  the  bays 

filled  with   gravel    or    loose 

rock  as  the  framing  progresses,  or  they  may  be  floated  light  into  position 

and  there  loaded  and  sunk;  they  can  be  made  water-tight  by  planking 

or  boarding,  or  by  diking.    To  resist  overturning,  with  a  factor  of  two, 

their  interior  width  should  equal  0.75  of  the  water  height  and  their  rock- 
filled  height  should  rise  three 
feet  above  the  water  surface. 
(F)  Timber  cribs,  Fig.  16, 
are  built  of  dimension  timber 
in  crib  fashion  similar  to  log 
cribs,  or  of  solid  timber  walls, 
and  are  filled  with  rock, 
gravel,  or  sand  and  made 
water-tight  by  canvas  cov- 
ering and  puddle  placed 
along  their  footing  on  the 
pressure  side.  To  resist 
overturning,  with  a  factor 

of  two,  the  width  of  timber  crib  should  be  0.66  of  the  water  height  and 

the  filled  height  should  equal  that  of  the  water. 

(G)   Timber. — Boards  are  one  inch  thick,  and  sawn;  planking  is  two 

or  three  inches  thick,  sawn ;  scantling  is  1"  x  3"  or  4",  sawn.    Dimension 

comprises  all  sawn  or  hewn  sticks  of  rectangular  or  square  section  ex- 


Fig.  16 


H.E.P.55 
H.V.S. 


Timber  Crib. 


138 


HYDRO-ELECTRIC   PRACTICE 


Fig.  17 


ceeding  three  inches  in  thickness;  ft.  b.  m.  is  the  abbreviation  for  feet 
board  measure,  the  unit  of  which  is  one  square  foot  one  inch  thick.  Round 
timber  measure  is  in  cubic  feet  =  length  X  § ;  C  is  the  circumference  of  the 
log  in  feet. 

(H)  Bearing  piles  are  straight  logs  16  feet  and  longer,  8"  in  diameter 
at  the  small  end  under  the  bark;  they  must  be  of  one  year's  cut  and 

sound  and  are  barked.  They 
are  driven  to  refusal  when 
they  do  not  sink  more  than 
0.5  inch  under  a  free  20- 
feet  drop  of  a  2000-pound 
hammer. 

The  theoretical  bearing 
capacity  of  timber  piles  equals 
cube  root  of  fall  of  hammer 
in  feet  x  weight  of  hammer 
in  pounds  x  constant  0.023, 
divided  by  constant  1  +  sink- 
ing distance  per  stroke  in 
inches,  which  for  "  driven  to 
refusal"  conditions  are  4/20 
X  2000  X  0.023  +  1.5  =  64 
tons.  The  actual  loading 
should  not  exceed  one-half 
of  theoretical  when  the  pile 
stands  in  gravel,  clay,  and 
sand;  one-fourth  of  theoreti- 
cal when  the  pile  stands  in 
clay  and  sand;  one-tenth  of 
theoretical  when  the  pile  stands  in  mud.  To  drive  bearing  piles  in  com- 
pacted sand  is  difficult  and  generally  requires  clearing  by  water  jet. 

(I)  Concrete  piles  are  constructed  by  different  processes.  In  Fig.  17 
a  collapsible  steel  core  inside  of  a  steel  plate  shell  is  driven,  the  core  is 
withdrawn  and  the  shell  filled  with  concrete.  In  the  other  type  a  steel 
form  fitted  with  a  bucket  point  is  driven  to  the  required  depth,  some 
concrete  is  then  lowered  into  it  and  the  shell  is  pulled  up  two  feet,  by 
which  operation  the  bucket  point  opens  and  permits  the  concrete  to  drop 
to  the  bottom  and  it  is  there  rammed  in  place;  lowering  more  concrete, 


I 

"o 
U 


H.E.P.56 
H.v.S. 


Concrete  Piles. 


STRUCTURAL  TYPES 


139 


Fig.  18 


pulling  shell  two  feet,  and  ramming  the  concrete  are  repeated  until  the 
pile  is  completed.  These  piles  can  be  re-enforced  by  imbedding  steel 
rods  in  the  concrete. 

(J)  Cut-off  wall  intercepts  flow  and  seepage  below  the  surface;  it 
may  be  of  puddle,  timber  or  steel  curtain,  or  a  concrete  wall. 

(K)  Core  wall  serves  the  same  purpose  as  the  cut-off  in  the  interior 
of  earth  embankments. 

(L)  Puddle  is  a  plastic  mass  of  clay,  small  gravel,  and  coarse  sand 
in  the  proportions  of  5  to  3  to  2,  compacted  in  a  confined  space. 

(M)  Timber  curtain  serves  the  purpose 
of  cut-off  or  core  wall,  and  consists  of 
triple-lap  sheet  piles,  Fig.  18,  which  are 
constructed  of  three  planks  placed  on  face 
sides,  centre  plank  overlapping,  thus  form- 
ing tongue  and  groove  on  opposite  edges; 
planks  are  secured  by  wrought-iron  boat 
spikes  one  inch  longer  than  thickness  of 
pile,  spikes  are  driven  from  opposite  sides 
of  pile,  points  are  clinched. 

Piles  up  to  8  feet  long  are  6  inches 
thick;  piles  up  to  16  feet  long  are  9  inches 
thick;  piles  up  to  24  feet  long  are  12 
inches  thick.  One  end  is  scarf  pointed  so 
that,  when  driven,  it  crowds  toward  pre- 
ceding pile,  forcing  the  tongue  into  the 
groove.  These  piles  should  be  driven  with 
a  light  hammer  and  a  low  drop  and  be 
guided  all  the  way  down;  the  timber  for  them  should  be  pine  or  hem- 
lock, sound,  of  uniform  thickness,  and  preferably  edged. 

(N)  Steel  curtain  is  constructed  of  steel  sheet  pile  sections  described 
under  D. 

(O)  Concrete  herein  considered  consists  of  true  Portland  cement 
mortar  and  hard  broken  stone  or  gravel ;  the  mortar  is  composed  of  one 
part  of  cement  and  two  or  three  parts  of  sand  by  weight  and  of  sufficient 
volume  to  fill  completely  the  voids  in  the  aggregate.  A  1  :  3  :  6  mixture 
is  designated  as  x  concrete,  a  1:2:5  mixture  is  called  xx  concrete. 
The  cement  and  sand  should  conform  to  the  standard  specifications  of 
the  American  Society  of  Civil  Engineers;  the  aggregate  is  sized  from 
one-quarter  inch  to  two  and  one-half  inches. 


Triple-lap  Sheet  Pile. 


140  HYDRO-ELECTRIC   PRACTICE 

The  mixing  is  by  hand  or  in  batch  mixers  as  follows :  the  cement  and 
sand  are  dry  mixed ;  water  is  added  and  the  mortar  mixed,  the  aggregate 
is  added,  thoroughly  washed  and  wet,  and  the  concrete  is  mixed  to  a 
wet  but  not  flowing  mass, — that  is,  water  should  not  stand  on  its  surface 
nor  ooze  out  of  it  during  handling  or  transporting. 

The  concrete  is  placed  in  a  manner  to  avoid  disintegration  of  the 
mixture  when  dropped  from  cars,  barrows,  or  shovels;  the  height  of  its 
fall  should  be  restricted,  and  the  inclination  of  chutes  must  not  be  steep. 

When  concrete  is  placed  on  rock,  the  surface  should  be  cleaned  of 
all  vegetable  and  earthy  matter  and  drenched  with  water,  and  smooth 
rock  surfaces  should  be  scarred. 

Unfinished  joints  are  to  be  treated  in  the  same  manner  as  rock  faces 
before  new  concrete  is  added,  and  the  maximum  length  of  unfinished 
joints  on  the  same  plane  should  not  exceed  ten  feet. 

Finished  concrete  should  be  covered,  if  practicable,  with  a  layer  of 
wet  sand)  or  otherwise  shaded  from  the  sun  and  kept  damp,  for  48  hours. 

Such  concrete  may  be  expected  to  develop  in  six  months  the  follow- 
ing characteristics,  expressed  in  pounds  per  square  inch: 

TABLE  4.— CONCRETE  CHARACTERISTICS. 

X   Concrete.  XX  Concrete. 

Modulus  of  elasticity EC  =  3,000,000  2,400,000 

Compressive  strength fc  =          2,000  2,400 

Tensile  strength ft  =            200  200 

Shearing  strength C  =            300  300 

Expansion =   0.000006  per  degree  F. 

Adhesion  to  rust-free  steel =  600 

Working  stresses  should  be  taken  at  0.25  of  above. 

Cyclopean  concrete  has  imbedded  in  the  concrete  mass  solid  stones 
of  any  size,  each  stone  being  surrounded  by  not  less  than  a  twelve-inch 
wall  of  concrete,  and  no  stones  being  placed  closer  to  the  finished  sur- 
faces of  the  structure  than  two  feet.  Monolithic  concrete  is  a  solid  mass 
of  concrete.  Block  concrete  consists  of  shaped  concrete  units  laid  in  the 
manner  of  ashlar  or  coursed  masonry  in  Portland  cement  mortar. 

Forms  are  shapes  of  boards,  planking,  or  metal  walls  in  which  con- 
crete is  moulded  into  blocks,  walls,  partitions,  arches,  or  beams;  the 
interior  sides  of  the  forms  are  smooth  and  oiled.  Forms  should  not  be 
removed  until  the  concrete  is  fully  set,  generally  48  hours. 

Concrete  steel,  or  reinforced  concrete,  is  a  structure  in  which  the 


STRUCTURAL   TYPES  141 

imbedded  steel  increases  the  strength  of  the  entire  section;  or  in  which 
the  proportions  of  the  steel  to  the  concrete  area,  and  the  location  of  the 
steel  with  reference  to  the  stresses,  are  determined  to  secure  the  action 
of  both  as  a  unit.  The  random  placing  of  steel  members  in  a  concrete 
mass,  or  the  lining  or  supporting  of  any  side  or  face  of  a  concrete  section 
with  steel,  is  not  of  the  class  herein  considered.  The  characteristics  of 
reinforcing  steel  are  taken  in  pounds  per  square  inch  as  follows: 

TABLE  5.— REINFORCING  STEEL  CHARACTERISTICS. 

Modulus  of  elasticity Es  =  29,000,000 

Ultimate  strength fs  =          64,000 

Elastic  limit F  =         50,000 

Expansion =   0.0000065  per  degree  of  F. 

The  concrete  steel  designs  herein  used  are  based  upon  the  concrete 
and  steel  characteristics  given  in  Tables  7  and  8,  and  are  according  to 
formulae  of  Mr.  A.  L.  Johnson,  M.  Am.  Soc.  C.  E. 

TABLE  6.— CONCRETE  STEEL  BEAMS. 

X  Concrete.  XX  Concrete. 

Moment  of  ultimate  resistance =   3620  t2  5505  t2; 

Area  of  steel  in  width  of  sec q  =  0.077  t  0.132  t; 

t  is  depth  of  the  beam. 

Values  of  t  and  q  for  beams  to  resist  various  bending  moments  in 
accordance  with  these  formulae  are  given  in  Table  7.  Many  different 
kinds  and  shapes  of  reinforcing  steel  rods  are  used  in  such  structures, 
but  the  above  formulae  apply  generally  and  differ  only  with  the  change 
of  concrete  and  steel  characteristics. 

TABLE  7.— VALUES  FOR  CONCRETE  STEEL  BEAM  DESIGNS. 

M  =  ultimate  bending  moment  of  external  forces  in  1000  inch  pounds;  t  =  depth  of  beam  in 
inches;  q  =  square  inches  of  steel  in  one  toot  width  of  beam.  Steel  is  placed  0.9  t 
from  compression  face  of  the  beam. 

X  Concrete.  XX  Concrete. 

M.  t  q  t  q 

100 5.27  0.408  4.27  0.562 

150 6.45  0.500  5.22  0.689 

200 7.45  0.576  6.02  0.795 

250 8.32  0.644  6.74  0.889 

300 9.12  0.706  7.38  0.975 

350 9.85  0.762  7.93  1.050 

400 10.52  0.816  8.52  1.125 

450 11.15  0.861  9.05  1.193 

500..  .11.73  0.910  9.53  1.258 


142  HYDRO-ELECTRIC   PRACTICE 

X  Concrete.  XX  Concrete. 

M.  t  q  t  q 

550 12.38  0.956  10.00  1.320 

600 12.90  0.998  10.44  1.3SO 

650 13.40  1.040  10.84  1.435 

700 13.92  1.078  11.29  1.486 

750 14.40  1.113  11.68  1.540 

800 14.88  1.151  12.02  1.588 

850 15.34  1.188  12.41  1.640 

900 15  80  1.222  12.79  1.686 

950 16.25  1.258  13.11  1.735 

1,000 16.68  1.289  13.49  1.780 

1,500 20.40  1.580  1650  2.180 

2,000 23.50  1.812  19.05  2.520 

2,500 26.30  2.038  21.30  2.810 

3,000 28.80  2.230  23.35  3.075 

3,500 31.15  2.410  25.20  3.325 

4,000 33.25  2.573  26.90  3.560 

4,500 35.25  2.730  28.59  3.780 

5,000 37.20  2.880  30.10  3.9SO 

5,500 39.10  3.025  31.60  4. ISO 

6,000 40.80  3160  33.05  4.360 

6,500 42.50  3.285  34.39  4.530 

7,000 44.00  3.410  35.65  4.700 

7,500 45.60  3.530  36.SO  4.870 

8,000 47.00  3.640  38.10  5.030 

8,500 48.55  3.760  39.30  5.190 

9,000 49.90  3.860  40.40  5.340 

9,500 50.25  3.965  41.50  5.585 

10,000 52.70  4.075  42.60  5.620 

(P)  Breakwater  consists  of  log  cribs  placed  ten  to  sixteen  feet  centres, 
the  intervening  spaces  being  closed  by  planks  or  timbers  placed  in  an 
inclined  position,  ends  resting  on  the  stream  bed  and  tops  against  longi- 
tudinal logs  secured  to  the  top  of  cribs;  its  purpose  is  to  check  swiftly 
flowing  water. 

(Q)  Sheet  pile  dike,  Fig.  19,  is  employed  for  coffering  service;  it 
consists  of  two  parallel  sheet  pile  curtains  from  five  to  fifteen  feet  apart, 
the  area  between  them  being  filled  with  puddle,  and  the  pressure  side, 
or  both  sides,  being  covered  with  riprap  and  facing  fill. 

(R)  Riprap  is  loose  rock  thrown  up  against  a  bank,  wall,  or  curtain, 
to  break  the  force  of  flowing  water  or  resist  its  pressure. 

(S)  Steel  pile  dike  is  a  structure  similar  to  the  sheet  pile  dike,  the 
curtain  being  of  steel  sheet  piles. 

(T)  Paving  consists  of  large  flat  stones  placed  by  hand  on  faces  or 
edges,  interstices  being  filled  with  stone  chips  or  spalls,  on  slopes  of  earth 
banks  or  surfaces,  to  prevent  erosion. 


View  1 
Breakwaier 


I  I.E.  P. 59 
H.v.S. 


View  2 
Timber  Crib 


View  3 
Log  Crib  Coffer 


View  4 
Sheet  Pile  Dike 


STRUCTURAL   TYPES 


143 


Water 
Surface 


Fig.  19 


ARTICLE  54. — Coffering  is  the  first  operation  preparatory  to  the 
construction  of  any  part  of  the  dam,  in  order  to  exclude  the  water  from 
the  construction  site.  It  requires  judgment  born  of  experience  to  con- 
fine the  means  employed,  which  will  accomplish  this,  to  devices  of  tem- 
porary character  and  economical  cost;  their  failure  will  generally  cause 
damages  which  would  cover  the  cost  of  the  most  permanent  works. 
Depth  of  water,  velocity  of  flow,  river-bed  material,  area  to  be  coffered, 
and  possibility  of  exposure  to  flood  rises  are  the  conditions  to  be  weighed 
in  determining  the  recommendable  programme. 

In  a  rock  bed  and  shallow  water  where  the  velocity  does  not  exceed 
three  feet  per  second,  a  dike  (53,  B)  answers  the  purpose  until  its  required 
section  exceeds  the  cost  of  a 
log  crib  (53,  E) ,  which  latter 
must  be  chosen  for  swift 
water.  In  rapids  a  break- 
water (53,  P)  should  first 
be  constructed,  such  as  is 
seen  in  View  1,  which  was 
erected  in  the  Sault  Rapids 
at  the  foot  of  Lake  Superior, 
being  300  feet  long  in  ten- 
feet-deep  water  with  velocity 
of  twelve  feet  per  second. 
Rock  is  not  always  the  most 
economical  filling  for  cribs,  as,  for  example,  in  the  case  of  the  location 
just  referred  to,  View  2,  where  the  construction  site  was  coffered  by  a 
timber  crib  filled  with  sand  which  was  pumped  in.  In  gravel  and  clay 
beds  a  dike  answers  until  its  cost  exceeds  that  of  a  log  crib,  as  the  one 
shown  in  View  3,  which  was  250  feet  long,  placed  in  ten  feet  of  water 
and  exposed  to  considerable  wave  action. 

In  clay  and  sand  and  depth  of  water  exceeding  ten  feet,  a  sheet  pile 
dike  (53,  Q)  will  prove  the  most  serviceable,  such  as  is  shown  in  View  4, 
which  was  placed  by  the  author  in  twenty  feet  of  water,  was  two  thousand 
feet  long,  and  consisted  of  two  timber  curtains,  fifteen  feet  centres,  braced 
and  strutted,  filled  with  puddle,  riprapped  and  banked;  it  remained  in 
service  during  a  period  of  three  years  and  developed  no  leaks.  When 
water  is  shallow,  timber  or  steel  sheets  (53,  C  and  D)  may  answer;  two 
examples  of  the  latter,  constructed  of  different  type  of  steel-sheet  piles, 


H.E.P.58 
H.v.S. 


Sheet  Pile  Dike. 


144  HYDRO-ELECTRIC   PRACTICE 

are  shown  in  Views  5  and  6.  In  compacted  sand  a  steel  sheet  may  prove 
the  only  practicable  coffer  up  to  ten  feet  depth  of  water;  when  deeper, 
a  steel  pile  dike  may  be-  the  proper  solution;  timber  sheets  cannot  be 
driven  successfully  in  this  class  of  material.  In  soft  formations  and 
water  depth  of  five  feet  or  less,  timber  sheets  will  answer;  in  greater 
depths  the  sheet  pile  dike  is  preferable  to  cribs,  as  it  will  be  difficult  to 
find  firm  footing  for  the  latter. 

In  all  coffer  operations  it  is  essential  to  provide,  and  constantly 
maintain,  ready  means  to  add  promptly  filling,  riprap,  and  facing  material 
to  the  coffering  structures,  and  further  to  provide  and  keep  in  commission 
a  sufficient  pumping  plant  to  remove  all  water  accumulating  from  leaks 
and  seepage  which  is  collected  in  a  pump  sump  conveniently  located. 

TABLE  8.— QUANTITIES  REQUIRED  FOR  DIFFERENT  COFFER  STRUCTURES  IN  10-FEET 
LENGTHS,  AS  PER  SECTIONS  SHOWN  IN  FIGS.  12  TO  19. 


_               SHEETS. 
Depth, 
Water,  Timber,  Steel, 
ft.    ft.  b.m.      Ibs. 

DIKE. 

Cub.  yds. 
Rock.  Puddle 

SHEET  PILE  DIKE. 

Timber,      Puddle,    Riprap, 
.  ft.  b.m.    cub.  yds.    cub.  yds 

LOG  CRIB.                    TIMBER  CRIB. 

Logs,  Drifts,  Rockfill,  Timber-Drifts,  Spikes.Sandfill, 
.    lin.  ft.    Ibs.    cub.  yds.      ft.  b.m.          Ibs.    cub.  yds. 

5.. 

1230 

1430 

5 

45 

2400 

10 

12 

125 

150 

7 

1750 

175 

5.5 

6.. 

1420 

1650 

7 

54 

2800 

*  13.3 

15 

155 

170 

11.7 

2175 

200 

9 

7.. 

1630 

1870 

9 

64 

3200 

17 

19 

174 

190 

15.5 

2475 

225 

13 

8.. 

1860 

2090 

12 

75 

3600 

21.6 

23 

198 

205 

20 

2825 

250 

17 

9.. 

1880 

2310 

15 

88 

4000 

27 

28 

220 

220 

25 

3150 

270 

21 

10.. 
11 

2300 

2530 

18 
22 
27 
31 
36 
42 

100 
113 
126 
141 
154 
171 

4400 
4700 
5000 
5450 
5800 
6200 
6700 
7100 
7500 
7900 
8400 

32 
37.8 
44.4 
51 
58.5 
66.6 
75 
83.7 
93 
102.8 
112.4 

33 
37 
42 
47 
53 
60 
66 
74 
82 
90 
98 

250 
275 
294 
317 
352 
375 
400 
425 
450 
475 
515 

230 
245 
260 
275 
290 
305 
320 
335 
350 
360 
380 

30.5 
35.5 
43 
52 
61 
71 
80 
89 
98 
107 
117 

3600 
4000 
4275 
4625 
5150 
5525 
5900 
6325 
6700 
7100 
7700 

290 
315 
335 
360 
380 
410 
430 
460 
480 
500 
530 

26 
31 
36.5 
42 
48 
55 
65 
75 
85 
95 
105 

12 

13 

14 

15 

16 

17 

18 

19 

20 

ARTICLE  55. — A  foundation  design  for  a  thirty-feet  high  spillway  in 
alluvial  location,  based  upon  the  theories  outlined  in  Art.  52,  is  shown 
in  Plan  18.  The  structure  consists  of  a  cut-off  wall,  bearing  piles,  floor 
walls  or  beams,  and  floor.  The  cut-off  may  be  a  driven  timber  or  steel 
curtain,  provided  the  river  bed  material  is  such  that  these  can  be  driven 
in  a  manner  guaranteeing  an  unbroken,  solid  curtain.  Timber  sheet 
piles  do  not  secure  this  result  if  driven  through  coarse  gravel,  or  if  bould- 
ers are  encountered,  as  these  will  deflect  the  driving  point  and  force  the 
tongue  out  of  the  groove,  leaving  openings  between  sheet  piles,  and  thus 


u  eq 

II 

-H    08 


Plan  18 
Foundation  design 


10 


H.E.P.65 
H.V.S. 

145 


146  HYDRO-ELECTRIC   PRACTICE 

defeat  the  purpose  for  which  they  are  employed.  Steel  piles  readily 
penetrate  gravel  without  deflection,  but  not  so  when  large  boulders  are 
struck,  as  their  interlocking  parts  may  then  be  ruptured  and  thus  also 
leave  openings.  These  defects  are  not  readily  detected  during  the  pro- 
cess of  driving,  and  therefore  the  decision  as  to  adaptability  of  driven 
curtains  for  cut-off  service  must  be  solely  based  upon  the  correct  diag- 
nosis of  the  material,  as  all  other  considerations  are  insignificant  in 
importance  when  compared  to  the  results  expected  from  the  foundation 
cut-off  wall. 

A  driven  curtain  presents  the  double  advantage  of  economy  and 
expedition,  as  it  can  be  frequently  driven  before  any  coffering  operations 
are  started  and  may  in  part  also  serve  to  aid  in  coffering  and,  when  of 
timber,  it  forms  the  most  economical  cut-off  wall  type.  The  tendency, 
therefore,  predominates  to  rely  upon  this  form;  but  these  influences 
must  not  be  permitted  to  outweigh  the  sound  judgment  of  the  engineer; 
when  the  presence  of  numerous  and  large  boulders  has  been  fully  estab- 
lished, a  driven  curtain  should  under  no  conditions  be  relied  upon. 

If  the  material  favors  the  use  of  a  driven  curtain,  the  piles  must  be 
constructed  and  driven  with  the  greatest  care,  and  this  operation,  above 
all  others,  demands  the  most  rigid  supervision  on  the  part  of  the  engineer. 

When  a  timber  curtain  cannot  be  used,  it  is  not  always  likely  that 
the  steel  curtain  solves  the  problem:  the  very  conditions  which  prohibit 
a  timber  curtain  form  difficulties  in  the  construction  of  a  perfect  steel 
curtain.  The  cost  should  be  estimated,  as  it  will  come  close  to,  and  per- 
haps exceed,  that  of  a  concrete  wall,  as  will  appear  in  a  comparative 
estimate  of  quantities  for  various  cut-off  structures  at  the  end  of  this 
article.  Steel  curtains  are  described  in  53,  D,  and  it  is  just  as  essential 
to  observe  every  detail  of  their  construction  as  with  timber  curtains. 
When  carefully  placed  they  form  an  effective  cut-off  wall;  but  they  are 
perishable,  nor  can  their  life  be  prolonged  by  any  protective  coating, 
as  this  would  be  more  or  less  removed  during  driving.  Steel  which  had 
been  imbedded  in  wet  clay  and  sand  for  six  years  was  found  reduced  in 
section  nearly  one-half  by  corrosion  when  recovered  by  the  author. 

When  driven  curtains  are  not  adapted  for  cut-off  wall,  trenching 
must  be  resorted  to  and  the  question  of  cut-off  type  further  examined. 
During  trenching  much  valuable  information  is  gained  as  to  the  exact 
subsurface  formation,  and  advance  borings  from  different  levels  will 
greatly  add  to  this.  When  the  required  depth  is  reached,  a  close  estimate 


STRUCTURAL   TYPES 


147 


can  be  made  as  to  which  is  the  most  economical  cut-off,  a  timber  curtain 
or  concrete  wall;  both  will  give  equally  satisfactory  results  as  cut-offs, 
as  the  timber  sheet  piles  can  now  be  placed  with  perfect  interlocking, 
and  their  durability  is  guaranteed  by  their  constant  saturated  condition. 
It  becomes  then  solely  a  question  of  cost,  which,  with  low-price  concrete 
and  high  cost  of  timber,  may  be  in  favor  of  the  former  or,  with  values 
reversed,  the  latter  may  be  more  economical. 

The  placing  of  timber  curtains  in  the  trench  needs  no  further  detail- 
ing nor  that  of  the  concrete  wall.  Trenches  should  be  three  feet  wide 
to  ten  feet  depth,  four  to  twenty,  five  to  thirty,  and  six  to  forty  feet 
depth,  in  order  to  provide  room  for  shoring  and  handling  of  material. 
Concrete  cut-off  walls  may  be  uniformly  three  feet  thick;  the  remaining 
trench-space  is  refilled  with  puddle  (53,  L). 


TABLE  9.— QUANTITIES  FOR  CUT-OFF  WALLS  IN  TEN-FEET  LENGTHS. 


DRIVEN  CURTAINS. 


Depth  in 
feet. 

6... 

8.., 


Timber, 
ft.  b.  m. 

600 
800 


10  ..................  1,000 

12  ..................  1,200 

14  ..................  1,400 

16  ..................  1,600 

18  ..................  1,800 

20  ..................  2,000 

22  ..................  2,200 

24  ..................  2,400 

26  ..................  2,600 

28  ..................  2,800 

30  ..................  3,000 

32  ..................  3,200 

34  ..................  3,400 

36  ..................  3,600 

38  ..................  3,800 

40  .................  4,000 


Spikes, 
Ibs. 

60 
80 

100 

120 

140 

160 

180 

200 

220 

240 

260 

280 

300 

320 

340 

360 

380 

400 


Steel, 
Ibs. 

660 

880 

1,100 

3,000 

3,500 

4,000 

4,500 

5,000 

7,700 

8,400 

9,100 

9,800 

10,500 

13,400 

14,280 

15,120 

15,960 

16,800 


TRENCHED  CURTAINS. 

Trenching,  Puddle, 
cub.  yds.   cub.  yds. 


7 
9 
11 
18 
21 
24 
27 
30 
41 
44 
48 
52 
55 
71 
75 
80 
85 
90 


5 

6 

7 

13.5 
15 
18 
20 
23 
33 
35 
38 
41 
49 
59 
62 
67 
71 
75 


CONCRETE  WALL. 

Concrete,   Puddle, 
cub.  yds.  cub.  yds. 


11 
13 

15.5 

18 

20 

22 

24 

27 

29 

31 

33 

35.5 

38 

40 

42 

45 


5 

5.5 

6 

7 

8 
15 
17 
19 
21 
22 
35.5 
37 
40 
43 
45 


ARTICLE  56.  Foundation. — When  a  sufficient  area  of  the  foundation 
site  is  safely  coffered  and  the  water  removed  by  draining  or  pumping  or 
both,  the  site  is  prepared  by  being  levelled  to  a  uniform  plane,  and  all 
vegetable  matter,  roots,  etc.,  removed;  then  the  bearing  piles  are  driven 
as  per  Plan  18  and,  as  specified  in  53,  H,  to  refusal.  Piles  must  be  driven 
with  care;  brooming  of  tops  should  be  avoided;  in  hard  driving  timber 
followers  should  be  used.  In  order  to  guard  against  the  driving  of  piles 


148  HYDRO-ELECTRIC   PRACTICE 

which  prove  too  short,  or  prevent  waste  by  using  those  which  are  too 
long,  advance  borings  should  be  made  by  which  the  character  of  the 
material  and  thus  its  penetrability  can  be  determined  with  certainty. 
In  very  soft  soils  every  other  longitudinal  pile  row  should  be  driven  at 
a  batter  leading  downstream,  by  which  additional  resistance  to  sliding 
of  structure  will  be  secured,  since  a  downstream  movement  would  have 
to  be  accompanied  by  a  rising  upward  of  pile  tops  and  thus  involve  lifting 
of  the  foundation  walls  in  which  they  are  imbedded  and  of  the  super- 
structure. All  piles  should  be  driven  before  any  of  the  concrete  is  placed, 
to  avoid  possible  rupture  caused  by  vibration  due  to  pile  driving.  Pile 
tops  are  cut  off  on  a  uniform  horizontal  plane  being  that  of  the  bottom 
of  foundation  floor. 

The  trenching  for  floor  walls  should  begin  at  the  upstream  cut-off 
wall,  if  it  is  a  trenched  structure,  and  only  so  much  trench  is  opened  as 
can  be  kept  entirely  free  of  water  by  pumping;  the  wall  concrete  is  of 
x  mixture  and  is  compacted  in  the  trench  on  both  sides  of  the  curtain 
top  and  covering  the  same.  If  the  superstructure  is  to  connect  with  the 
cut-off  wall,  as  is  generally  the  case,  re-enforcing  steel  rods  are  imbedded 
in  this  cut-off  concrete.  The  other  floor  walls  or  beams  are  placed  like- 
wise successively,  steel  rods  or  dowels  being  imbedded  in  them  two  feet 
centres.  This  concrete  should  not  be  too  wet,  as  the  soil  itself  will  con- 
tain more  or  less  water,  and  as  all  of  it  should  be  given  considerable  ram- 
ming. The  top  surfaces  of  floor  walls  must  be  left  as  rough  as  possible. 

The  foundation  floor  consists,  as  shown  in  Plan  18,  of  separate  arches, 
longitudinal  to  the  floor,  the  walls  forming  the  skewbacks.  Beginning 
at  the  upstream  end,  the  soil  between  cut-off  and  first  upstream  wall  is 
trimmed  away  to  the  arch  form,  and,  the  section  being  kept  entirely 
free  of  water,  the  respective  floor  arch  is  laid  of  x  concrete,  the  wall  tops 
being  first  cleaned,  roughened,  and  thoroughly  wetted,  and  the  concrete 
rammed  into  place.  Along  the  top  of  each  floor  wall  a  groove  is  left  free 
of  concrete,  one  foot  wide  and  deep,  to  form  a  connecting  key  for  the 
superstructure,  and,  when  the  latter  consists  of  transverse  buttresses  or 
partitions,  similar  grooves  are  formed  in  the  floor  transversely.  In  this 
manner  the  entire  foundation  floor  is  constructed.  Quantities  in  such 
foundations  for  spillways  of  different  heights  are  given  on  Diagram  12. 

ARTICLE  57.  Superstructure. — The  subjects  to  be  considered  for  the 
selection  of  a  recommendable  type  are  the  height,  length,  section,  char- 
acter of  material  in  river  bed,  flood  volume  to  be  controlled,  fluctuations 


STRUCTURAL   TYPES  149 

of  fall,  floatage  and  ice,  legal  requirements,  location  of  the  power  station, 
availability  of  structural  material  and  skilled  labor,  and  of  transporta- 
tion facilities  to  the  site. 

The  height  is  fixed,  generally  speaking,  by  the  available  power  fall 
and  the  depth  of  water  in  the  river  at  the  site.  The  fall  is  to  be  based 
upon  conditions  prevailing  when  the  volume  of  flow  is  that  which  is  to 
be  diverted,  and  is  represented  by  the  total  fall  in  the  stream  over  the 
reach  to  be  controlled  less  the  slope  which  will  prevail  in  the  upper  pool, 
proper  weight  being  given  to  the  flood  conditions.  The  slope  or  back- 
swell  is  the  fall  in  the  pond  above  the  dam  which  creates  the  flow;  this 
is  most  readily  determined  from  the  application  and  solution  of  the  flow 
formula  for  a  sufficient  number  of  stream  sections  in  the  length  which 
will  be  covered  by  the  upper  pool.  For  this  purpose  a  contour  plan  of 
the  stream  valley,  to  the  height  to  which  the  pond  level  is  to  be  raised, 
must  be  available,  and,  assuming  then  section  B  B  at  some  point  above 
the  dam  site,  the  cross-section  is  plotted  as  on  Plan  19,  from  which  the 

wetted  perimeter  is  scaled P  =  feet, 

the  flow  area  to  the  future  pond  level  is  computed A  =  square  feet, 

and  the  hydraulic  radius  is  found  from  A  -=-  P R  = 

Assuming  the  flow  volume  which  is  to  be  diverted 

when  no  water  passes  over  the  spillway  as Q  =  cub.  sec. ft., 

the   velocity  with  which   it   passes   through   the 

section B  B  is  V  =  f t.  per  sec. 

The  flow  formula  best  adapted  to  solve  the  problem 

is  that  of  M.  H.  Bazin: R  S  =  (a  +  ~)  V2, 

in  which 

R  is  the  hydraulic  radius, 

S  is  the  slope  of  the  water  surface, 

a  and  b  are  constants  expressive  of  the  retarding 

influence  of  P,  and 
V  is  the  velocity  of  the  flow. 

All  the  factors  in  this  formula  are  known  with  the  exception  of  S,  and 
this  is  the  value  which  is  sought,  as  from  it  the  fall  in  the  pool's  surface, 
which  causes  the  flow  toward  the  dam,  is  found. 

"S"  can  be  taken  from  Diagrams  20  to  25  for  the  different  river- 
bed characteristics,  whether  in  rock,  gravel  and  sand,  or  clay  and  sand. 


150  HYDRO-ELECTRIC    PRACTICE 

According  to  the  length  of  the  pond  and  the  uniformity  of  its  prism,  S 
is  determined  for  the  centre  section  of  lengths  of  1000  feet  or  more,  or 
of  such  as  represent  approximate  similarity  of  channel  in  area  and  shape, 
and  the  slope  found  for  it  is  credited  to  that  reach,  and  thus  the  aggre- 
gate slope  or  swell  is  determined  for  the  entire  pool  until  its  upper  terminal 
is  reached,  which  will  be  detected  by  the  rapid  increase  of  S. 

Example.  —  Length  of  pond  deduced  from  the  horizontal  plane  of 
the  produced  spillway  crest  level  is  12  miles;  the  flow  to  be  diverted, 
none  passing  over  the  spillway,  is  2600  cubic  second  feet,  the  height  of 
the  dam  crest  above  the  river  surface  with  this  flow  is  20  feet  ;  the  length 
of  the  spillway  is  200  feet.  For  the  first  5000  feet  above  the  dam  the 
pond  lies  between  uniformly  sloping  banks  and  is  of  approximately  uni- 
form cross  areas,  the  perimeter  is  of  gravel  and  sand  formation;  section 
A  is  therefore  taken  midway,  or  2500  feet  above  the  dam,  where 

P  =  243,     A  =  3466,     R  =  14.2,     and     V  =  0.75, 


S  =  (0. 
\ 


000122  +      7          -      =  0.000007  ; 
14.2  /  14.2 

the  total  fall  in  this  reach  of  5000  feet  is  therefore  =  0.035  ft. 

The  next  3000  feet  of  the  pond  is  of  smaller  flow  area,  the  pond  is  nar- 
rower, the  material  the  same;  a  section  B  is  taken  midway,  or  6500  feet 
above  the  dam,  where 

P  =  161,     A  =  2500,     R  =  15.5,     and     V  =  1.0, 
S  =  0.000011,  the  fall  in  this  reach  =  0.033  ft. 

Then  the  pond  widens  again  for  the  next  4000  feet,  and  at  mid-section 
C,  or  10,000  feet  above  the  dam, 

P  =  240,     A  =  2780,     R  =  11.6,     and     V  =  1.0, 

S  =  0.000009,  the  fall  in  this  reach  therefore  =  0.036  ft. 

Thus  for  12,000  feet  of  the  pond  the  total  fall  or  swell  =  0.104  ft. 

In  this  manner  the  process  is  continued  to  the  head  of  the  pond,  or  about 
twelve  miles  in  this  case.  From  this  point  up  the  original  stream  condi- 


151 


152 


153 


Sand  and  Gravel 
Perimeter 


154 


Sand  and  Gravel 
Perimeter 


155 


156 


20 


20 


157 


158  HYDRO-ELECTRIC   PRACTICE 

tions  continue,  which  means  that  the  velocity  will  be  much  greater  and 
therefore  also  S;    for  instance,  where 

P  =  256,     A  =  866,     R  =  3.4,     and     V  =  3.0,     8  =  0.00085, 

and  thus  the  approximate  head  of  the  pond  can  be  readily  fixed. 

In  addition  to  determining  the  backswell  for  the  volume  of  the  nor- 
mal flow,  it  must  also  be  found  for  other  river  stages,  especially  for  the 
high  flow,  in  order  that  the  full  effect  of  ponding  the  water  to  a  certain 
height  at  the  dam  may  become  clear. 

If  the  flood  flow  is,  for  instance,  in  this  case  =  9600  c.  sec.  feet, 
the  volume  passing  over  the  spillway  is  9600-2600  =  7000  c.  sec.  feet, 
or  35  c.  sec.  ft.  per  linear  foot  of  spillway  crest,  the  overfall  being 

=  4.9  feet. 

At  section  A  the  volume  of  water  will  be  increased  approximately 
by  a  depth  of  five  feet,  and,  assuming  the  banks  to  slope  up  uniformly, 

P  =  257,     A  =  4500,     R  =  17.9,    and    V  =  2.13,     S  =  0.000032, 
and  the  fall  in  first  reach  =  0.160; 

at  section  B,  under  like  conditions  and  assumptions, 

P  =  165,     A  =  3200,     R  =  19.4,     and     V  =  3.0,     S  =  0.000073, 
and  the  fall  in  this  second  portion  of  pond  =  0.219; 

at  section  C,  again  assuming  uniform  enlargement  of  area, 

P  =  258,     A  =  3900,     R  =  15.1,     and     V  =  2.46,     S  =  0.000067, 

and  the  fall  in  this  reach  =  0.264 : 

therefore  the  total  fall  in  the  12,000  feet  of  pond  =  0.643 
as  against  0.104  during  the  normal  flow  stage. 

Carrying  this  investigation  to  the  head  of  the  pond,  assumed  for 
normal  stage,  the  flood  rise  at  that  location  will  become  apparent,  and 
this,  compared  with  the  known  flood  height  at  that  point  before  the  dam 
is  erected,  will  show  what  increase  will  be  caused  by  such  a  dam. 

It  is  the  author's  experience  that  this  subject  of  backswell  receives 
generally  but  scanty  attention,  and  often  is  altogether  ignored,  in  con- 


STRUCTURAL   TYPES  159 

sequence  of  which  the  first  flood  brings  in  its  wake  numerous  damage 
claims  for  inundations  of  lands,  highways,  and  railroad  tracks,  while 
bridges  and  buildings  may  be  endangered,  all  of  which  might  have  been 
avoided  had  a  proper  knowledge  of  the  extent  of  the  backswell  been 
secured  before  the  dam  was  constructed,  as  considerable  control  of  it 
can  be  secured  by  its  proper  design,  as  will  appear  later  in  this  discus- 
sion. At  any  rate,  the  consideration  of  the  height  of  the  spillway  is 
incomplete  unless  the  backswell  is  fully  determined. 

ARTICLE  58. — The  length  of  the  spillway  is  primarily  that  which  is 
required  to  pass  the  maximum  flood  flow  within  the  limit  of  a  certain 
height  of  overfall  over  the  spillway  crest,  and  this  height  will  be  largely 
determined  by  the  elevations  of  the  natural  banks  or  of  the  embank- 
ments to  be  erected  and  by  the  volume  of  the  flood  flow ;  aside  from  this 
consideration  the  spillway  should  be  as  short  as  possible.  However, 
in  alluvial  formations  it  will  generally  be  most  advisable  to  make  the 
spillway  length  equal  to  the  width  of  the  stream  bed,  as  contracting 
this  is  always  fraught  with  danger  which  will  have  to  be  counteracted 
by  costly  abutment  and  embankment  structures. 

The  flood  flow  is  found  from  a  rating  table  of  the  river's  discharge 
compiled  from  flow  measurements  (Art.  41)  or  from  flow  computations 
(Art.  44) ;  from  this  the  volume  to  be  diverted  for  the  power  develop- 
ment is  deducted,  the  residue  is  to  be  passed  over  the  spillway.  The 
maximum  overfall  height  having  been  determined,  the  weir  discharge 
for  this  height  per  foot  length  is  found  (Diagram  2),  the  total  volume  to 
be  passed  is  divided  by  this,  and  the  quotient  represents  the  required 
spillway  length. 

Example. 

Flood  flow  assumed  at =  9000  cub.  sec.  ft. 

Diverted  flow  assumed  at =  1000  cub.  sec.  ft. 

Volume  to  be  passed =  8000  cub.  sec.  ft. 

Maximum  overfall  height =      3.5  feet 

Spillway  discharge  per  foot  of  length =    21.5  cub.  sec.  ft. 

Spillway  length  required 372  feet. 

As  the  spillway  will  be  provided  with  waste  flumes,  by  the  aid  of 
which  the  pond  can  be  drawn  down,  their  discharge  capacity  will  be 
available  for  additional  flood  passage,  and  they  therefore  represent  a 
safety  factor  in  this  respect. 


160  HYDRO-ELECTRIC   PRACTICE 

ARTICLE  59.  —  The  amount  of  pressure  and  resistance  is  the  first  sub- 
ject to  be  considered  when  the  spillway  section  is  to  be  designed.  The 
pressure  P  of  a  column  of  water  restrained  in  its  natural  passage  is  repre- 
sented by  the  product  of  the  pressure  area  A'  and  the  weight  of  water 
W;  the  area  factors  are  height  of  water  column  H  and  the  length  of 
pressed  surface. 

In  Fig.  20  S  is  vertical,  H  =  S,  ordinates  and  abscissae  represent 
factors  of  pressure  area  A'  which  intersect  in  pressure  plane  a  b. 

A'  =  S  (base)  X  ~  (half  altitude)  =  -?-. 

-  2 

When  the  water  level  is  below  the  top  of  the  pressed  surface,  the  pres- 
sure area  decreases  in  like  ratio,  both  S  and  H  being  reduced  by  hu  or 

H  =  S  --  ht  and  A'  =  J  (S  -  h)>. 

When  the  water  stands  above  the  pressed  surface,  the  pressure  area 
becomes  a  trapezoid. 

In  Fig.  21  S  is  vertical,  S  =  H  -  h, 

A'  =  H  -  h  (base)  X  H  J"  h  (altitude) 

H2-h2 
2 

or  expressed  in  S 


-      +  Sh. 

The  same  result  is  illustrated  geometrically  in  Fig.  22,  where  tri- 
angle b  g  1  represents  area  due  to  H  —  h  and  S.     Trapezoid  b  c  f  1  is  area 

Q2 

when  H  =  S  +  h  =  J  -  +  S  h,  by  which  the  rectangle  b  c  k  1  =  S  h 

a 
which  =  parallelogram  b  c  f  g,  is  added  to  triangle  b  g  1.     Or  for  expres- 

TT2    _     U2 

sion  in  values  of  H,  A'  =  -  -,  being  the  trapezoid  b  c  f  1  which  con- 

& 

TT2  Jj2 

sists  of  half  the  square  a  e  f  1  =  --  -  less  half  the  square  a  b  c  d  =  —  . 

2  A 


STRUCTURAL   TYPES 


161 


Fig.  20 


"ti.E.P.73 
H.v.S. 


H 


tJ.E.P.74 
H.V.S. 


T~ 


Fig.  22 


H.V.S. 


Fig.  23 


H.E.P.76 
H.V.S. 


11 


162  HYDRO-ELECTRIC   PRACTICE 

The  same  pressure  area  expressions  apply  when  the  pressed  surface 

is  inclined,  but  the  values  vary  with  the  inclination  of  S. 

S  H 

In  Fig.  23  A'  is  a  triangle,  S  is  base,  H  is  altitude;  A'  =  —  -. 

tt 

In  Fig.  24  A'  is  a  trapezoid,  S  is  base,  —  ^—  is  altitude  ;  A'  =  S  X       0   . 

Z  2i 

The  product  of  the  pressure  area  and  the  weight  of  water  (62.5 
pounds  per  cubic  foot)  is  the  pressure  "P"  against  the  surface,  which 
when  the  latter  is  vertical  and 

H  =  S  P  =  31.25  H2  ..............................  F.  1 

H  =  S  --  h         P  =  31.25(8  --  hj2  ........................  F.  2 

H  =  S  +  h         P  =  31.25  (H2  --  h2)  .......................  F.  3 

When  S  is  inclined  and 

H  =  ,|  P  =  31.25  H  S  .......................  F.  4 

V2 

H  =  S  --  h,  V2  P  =  31.25  H  (S  -  ht  V2)  .............  F.  5 

H=l+  h  P  =  31.25  S(H  +  h)   .................  F.  6 

A2 

The  intensity  of  the  pressure  of  any  volume  is  concentrated  in  its 
gravity  plane  passing  at  right  angles  to  the  pressed  surface  through  its 
centre  of  gravity  G. 

In  a  triangle  lines  drawn  from  apex  to  bisect  opposite  sides  are 
gravity  lines,  and  the  centre  of  gravity  lies  at  their  intersection  and  one- 
third  of  the  altitude  above  the  base. 

In  a  trapezoid  the  centre  of  gravity  is  found  as  in  Fig.  25  by  extend- 
ing the  base  lines  in  opposite  directions  to  equal  their  sum,  connecting 
the  ends  of  these  extensions,  d  i,  and  connecting  bisects  of  the  base  lines 
as  b  f  ;  the  intersection  of  d  i  and  b  f  marks  the  centre  of  gravity. 

The  height  of  the  centre  of  gravity  above  the  base  g  e  = 

X  -  (h'  =  altitude  of  trapezoid). 


ac  +  ge         3 


When  the  pressure  acts  upon  a  body,  its  force  is  expressed  by  the  product 
of  its  intensity  and  the  lever  arm  through  which  this  pressure  is  applied. 


STRUCTURAL  TYPES 


163 


H.E.P.78 
H.v.S. 


Fig.  27 


K— H--WJH.E.P.84 
H.V.S. 


164  HYDRO-ELECTRIC    PRACTICE 

The  lever  arm  L  is  the  vertical  distance  from  the  pressure  line  to 
the  turning  point  M  of  the  pressed  body. 

In  Fig.  26  S  is  vertical,  A'  is  triangle,  S  =  H,  G  =  ~,  and,  as  the 

TT 

pressure  passes  through  G  in  a  direction  vertical  to  S,   I/  =  —  ,  and 
the  dynamic  force   M  P  =  —  ^?,  and  of  water  M  P  =  10.417,  H3  .  .  .F.  7 
In  Fig.  27  S  is  vertical,  H  =  S  --  hu  L'  =  ^~^t 

MP  =  10.417  (S  -  hj3  .....  F.  8 

In  Fig.  28  S  is  vertical,  H  =  S  +  h,  L'  =  *L  +  2h  X  | 

H  +  h         3 

M  P  =  10.417  (H3  --  3  H  h2  +  2  h3)  .....  F.  9 

Diagrams  26  to  29  give  M  P  for  different  values  of  H  and  h. 

In  Fig.  29  S  is  inclined;  the  pressure  acts  vertical  to  S  at  M  through 
the  lever  arm  I/,  the  value  of  which  varies  with  inclination  of  S. 

In  Fig.  30  P  intersects  M  and  L,  therefore  becomes  zero,  and  as  S 
becomes  more  inclined  P  intersects  the  base  of  the  body.  For  the  practi- 
cal solution  of  the  dynamic  forces  acting  on  inclined  surfaces  the  pres- 
sure is  analyzed  into  its  horizontal  and  vertical  components,  h  P  and  v  P. 

In  Fig.  31  S  is  inclined  45°  and  =  H  \/2,  P  is  the  total  pressure 
acting  perpendicular  to  S;  a  b  c  d  is  a  square  of  which  P  is  the  diagonal, 

andhP  =£,  S  =  H  V2,fromF.  4,  P  =  31.25  SH  and  hP  « 

V2 


31  25  H?  x 
Inserting  value  of  S,  =  -         ~~o~^~~  =  31.25  H2,  which  is  the  same  as  P 


in  F.  1,  when  S  is  vertical  and  =  H. 

The  horizontal  component  of  P  equals  P  in  Fs.  1,  2,  and  3  as  per 
height  of  water,  no  matter  what  the  inclination  of  S  is.  The  vertical  com- 
ponent of  P  is  the  weight  of  the  water  area  overlying  the  base  e  f. 

M  P  for  inclined  surfaces  is  the  product  of  h  P  and  L,  and  there- 
fore the  same  as  expressed  in  Fs.  7,  8,  and  9,  to  wit:  when 

H  =,|  MP  =  10.417  H3  .  ......  F.  7 

V2 

H  =S-  ht  V2     MP  =  10.417(8  --  hj"  ...................  F.  8 

H  =  I  +  h  M  P  =  10.417  (H3  -  3  H  h2  +  2  h3)  ........  F.  9 

V2 

When  a  structure  is  to  restrain  water,  P  and  M  P  must  not  only  be 
counteracted  but  resisted  by  greater  forces,  otherwise  the  effect  of  these 


21 
H 

19 
18 
17 
16 


->.? 


/' 


// 


// 


13 

H 

12 

11 


// 

/v 


Diagram  26 


Solid  Spillway 


Pressure  Moment 


10 


MF|  \a\  ^qo|o[4i|)4 

o          o          o           o          o          -o         'o '     '  'o '  '  '  '6 


H.1-]*^ 
H.vS 


165 


38| 

/       / 

/ 

j       t 
/   /  ' 

/       /       - 

'//' 

' 

37 

/' 

/                T           * 

// 

/X    , 

/              '        J         ' 
'              J         /     .  f 

/ 

H 

1C 

/ 

/ 

£.    t 

/          /    /' 

35 

7 

/ 

/ 

/    /  /  ' 

/ 

/       / 

7 

/ 

^X 

11  — 

/    /    / 

^/   %    fy/j 

^ 

32 

/        /     J    *  / 

31 

7    /  .    / 

/ 

/   //  f 

30  - 

/     / 

1—/L 

7     / 

/  ~/~7i 

'    / 

'  /  1' 

/      ,      > 

/  // 

2" 

f    7  71 

/. 

/  /  /  /, 

L  I  uJL 

// 

/  /  /// 
L  L  Ul 

Diazram  27 

27  - 

/    1    I/A 

L  L  UL 

Solid  Spillway 
Pressure  Moment 

26 

H 

1 

Pllt 

U'l 

25 

i  77  / 

1 

III 

i 

24  - 

I    1 

lit 

1    LI 

ti' 

23 

'/// 

1 

L-.                * 

]»  in  10(0  ft.bs 

IE 
11, 

;'s! 

0 

22 

o 
o 

O               0 

in            o 

o        o             o           o 
in         o              mo 

O               O               O 

in            o            in 

166 


52 

f 

/ 
/ 

/ 

/ 

t 

/', 

// 
y 

^ 

51 

/ 

-  J-    J- 

f 

/ 

'  / 

M 

I. 

^ 

5U 
H 

/ 

'  /  A 

V 

< 

49  - 

/ 

/ 

/ 

| 

/  ff 
t 

48  - 

/ 

/ 

'/ 

47   - 

s 

? 

if 
/' 

I 

f 

46  - 

AS 

/ 

T 
t  / 

f 

/ 

y> 

i 

''"V 

/(' 

1 

A  A     — 

1 
i  / 

/ 

/ 

Li 

'ft 

tf 

44 
A.1   - 

f      r 
-J.-i.j-L 

/ 
// 

Diagram  28 
Solid  Spillway 
Pressure  Moment 

A?)    - 

/ 

III// 
/     '   /  ' 

A1     - 

/  7 
/// 

/     /._j 

/'// 

// 
ft 

H 

Af\ 

, 

/  '/I1! 
1  //I 

if 

39  - 

/ 

7 

/ 

lift 

/// 

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/ 

/ 

75 

7/ 

f 

A 

y 

ii 

100< 

t 

it 

I 

F 

H 

El 

»81 

i  j 

38OOOOOOO 
o           o           o           o           o           o           o 

IO                 \O                t^                 00                 ^^                 ^>                '"'^ 

o           o 

O                0 

o 
o 

167 


/ 

/ 

J 

// 

/ 

j 

1 

/  , 

/ 

/ 

/ 

/ 

/ 

/ 

/ 

/ 

/ 

V 

t 

/ 

/ 

/ 

0 

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/ 

/ 

/ 

/ 
/ 

i. 

/ 

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t 

/ 

/ 

/ 
/ 

]' 

H 

/ 

. 

/ 

/ 

/ 

7 

/ 

/ 
/ 

/ 

/ 
u 

/ 

58  - 

/ 

i 

f 
f 

\i 

/ 
/ 

z 

i/ 

/    t 

1    f 

f  i 

/ 

7/ 

// 

I 

/ 

// 

'/ 

/ 

I  i 

/    / 

v/ 

57 

/ 

> 

/  *? 

l\ 

1 

< 

/ 

/y< 

'A 

/ 

-, 

' 

/  / 

7/ 

s? 

I 

/ 

J_ 

/A** 

56 

•  f 

t 

/ 

// 

//'* 

/ 

/ 

/ 

/ 

/  f) 

1 

1 

/ 

/ 

1 

/I 

/ 

t 

1 

f 

/ 

i 

/ 

/ 

t 

1 

1   , 

/ 
'  / 

''/ 

I 

/ 

/ 

/ 
t  1 

/// 

/ 

Diagram  29 

KA     _ 

/ 

1 

1 

/// 

/I 

Solid  Spillway 

34 

H 

/ 
/    / 

'      I 

/    / 
I 

1 

/'/ 

/, 

// 

/ 

e^  _ 

/ 

'  /'/ 

Pressure  Moment 

53 

/ 

'  III, 

// 

f 

/ 

'      i 

I    / 

( 

\ 

\\\ 

r    K 

KiO  ft 

bi 

H 

I 

1.1 

.V 

> 
S 

?: 

52           o-           o 

0                0 

oooooooo 
oooooooo 

168 


STRUCTURAL   TYPES 


169 


will  be  to  displace  the  structure  by  sliding  it  along  the  base  or  any  hori- 
zontal plane,  by  overturning  it  around  its  toe,  crushing  its  material,  or 
rupturing  the  structure. 

ARTICLE  60. — Sliding  would  be  caused  by  h  P,  which  must  be  met 
by  the  effective  weight  W  of  the  resisting  body,  being  the  product  of  its 
material  weight,  plus  the  vertical  water  pressure  v  P  on  its  horizontal 
projection,  and  the  friction  coefficient  "f  "  developed  at  the  horizontal  joints 
and  at  the  base  between  the  structure  and  the  material  on  which  it  rests. 
When  the  structure  is  a  homogeneous,  impervious  mass,  its  material 
weight  is  the  product  of  its  area  A  and  the  unit  weight  W  of  the  substance 
composing  it,  which  is  not  diminished  by  standing  in  water;  if  water 


enters  under  its  base  and  remains  there  confined,  an  upward  pressure 
is  created  which  is  equal  to  the  product  of  the  area  of  the  base,  the  depth 
of  its  centre  of  gravity,  and  62.5  pounds;  if  it  freely  escapes  from  under 
the  base,  no  such  upward  pressure  exists.  The  friction  coefficient  f  is 
the  proportion  of  ultimate  friction  between  two  masses  to  the  perpendic- 
ular pressure, — i.e.,  the  weight  of  the  upper.  Ex.:  if  it  requires  a  force 
of  600  pounds  to  move  a  1000  pound  stone  resting  upon  a  horizontal 
surface,  f  =  TVA  =  0.60;  when  surfaces  are  connected  in  any  manner, 
resistance  to  sliding  is  represented  by  the  cohesion  of  the  bond  or  con- 
nection which  is  added  to  the  frictional  resistance. 

In  the  designs  herein  to  be  considered  for  spillways  the  structures 
are  assumed  to  consist  of  a  homogeneous,  impervious  mass;  water  is 
prevented  from  entering  beneath  the  base;  the  foundation  is  connected 
to  the  underlying  material  and  the  superstructure  is  bonded  to  the 
foundation. 


170  HYDRO-ELECTRIC   PRACTICE 

Resistance  to  sliding  is  theoretically  found  in  the  weight  of  the 
superstructure  plus  the  vertical  water  pressure;  but  in  practice  it  is 
recommendable  to  ignore  the  latter,  excepting  in  those  designs  which 
are  specifically  based  upon  gravity  theory,  that  is  when  the  pressed 
surface  is  inclined  from  the  vertical.  As  a  general  rule,  therefore,  the 
weight  of  the  structure  is  to  equal  the  horizontal  component  of  the  water 

pressure, 

Aw  =  or  >  h  P. 

ARTICLE  61. — Overturning  of  structure  is  caused  by  the  dynamic 
force  of  the  horizontal  component  of  the  water  pressure,  h  P  L/,  and  is 
theoretically  resisted  by  the  moment  of  weight,  M  W,  being  the  sum  of 
the  products  of  weight  of  structure  into  its  lever  arm,  A  w  L,  and  of  the 
vertical  water  pressure  into  its  lever  arm,  v  P  L",  or 

M  W  =  A  w  L  +  v  P  L", 

provided  the  resultant  of  these  two  forces  cuts  the  base  of  the  structure. 

In  Fig.  32  G  is  the  centre  of  gravity  of  the  structure,  M  its  fulcrum 
or  toe,  O  is  the  locus  of  the  gravity  plane  in  the  base  of  the  structure, 
O  M  =  L  the  lever  arm  through  which  W  acts. 

In  Fig.  33  G  O  =  L'  is  the  lever  arm  of  P  or  h  P,  O  M  =  L  is  the 
lever  arm  of  A  w,  N  M  =  I/  is  the  lever  arm  of  v  P,  G  P  =  P  or  h  P, 
G  W  =  A  w  or  A  w  +  v  P,  G  W  =  R,  the  resultant  of  h  P  and  G  W, 
O'  =  the  locus  of  the  resultant  in  the  base  of  the  structure. 

When  the  pressed  surface  is  inclined,  v  P  is  credited  to  W  as  adding  to 
the  resistance  against  overturning,  the  structure  being  of  a  gravity  design. 

The  resultant  must  always  fall  into  the  middle  third  of  the  base, 
for  reasons  given  in  next  article. 

Resisting  sliding  and  overturning  guarantees  stability  of  position  by 
AwL  =  or>hPL'  and  O'  falling  in  middle  third  of  the  base. 

ARTICLE  62. — The  crushing  or  rupturing  of  the  structure  may  be 
caused  by  the  concentration  of  excessive  pressures  on  parts  of  it. 

In  Fig.  34  the  weight  W  of  the  rectangular  structure  c  d  e  f  acts  in 
the  gravity  plane  on  the  centre  of  the  base  B  and  is  transmitted  to  the 
material  on  which  the  structure  rests.  The  pressure  due  to  W  is  repre- 
sented by  the  reaction  rectangle  e  f  i  j  =  W,  in  which  the  ordinates  P,  P', 
etc.,  represent  the  pressure  and  its  distribution  in  magnitude  as  per 
length  of  ordinates.  If  the  material  beneath  the  structure  does  not  yield 


STRUCTURAL  TYPES 


171 


Fig.  32 


'    H.E.P.89 
H.V.S. 


Fig.  33 


H.E.P.90 
M'  H.V.S. 


Fig.  35 


H.E.P.92 
H.V.S. 


172  HYDRO-ELECTRIC   PRACTICE 

to  these  pressures,  they  react  on  the  structure,  and  the  resistance  therein 
developed  must  be  sufficient  to  safeguard  the  material  against  crushing. 

Rigidity  of  foundation  is  herein  presupposed,  and  therefore  the 
pressures  tend  to  crush  the  structure's  mass. 

In  Fig.  35  the  structure  is  a  trapezoid  c  d  e  f ,  W  acts  on  the  base  B 

T> 

at  some  point  near  e  =  —  —  b;    the  pressure  is  represented  by  the 

£t 

reaction  trapezoid  e  f  i  j, 


The  pressure  is  not  uniformly  distributed  over  the  base,  but  is  maximum 
at  the  end  nearest  to  the  gravity  plane  and  minimum  at  the  other,  its 
ratio  between  these  being  proportional.  The  mean  pressure  ordinate  lies 
in  the  gravity  plane  produced,  because  the  sums  of  pressures  on  both 
sides  of  this  plane  are  equal  as  represented  by  reaction  diagram;  the 
distribution  of  the  pressures  therefore  depends  upon  the  locus  of  the 
gravity  plane  in  the  base  B  and  essentially  on  its  distance  from  the 
centre  of  B. 

Fig.  36  represents  the  reaction  trapezoid  e  f  i  j,  the  locus  of  the 
gravity  plane  is  at  O  and  its  distance  from  the  centre  of  the  base  B  =  b, 
which  is  determinable  from  the  formula  for  distance  of  centre  of  gravity 
above  the  base  of  a  trapezoid,  to  wit: 

e  O  =  y  =  P  +  2  P/  X  ?  (P  and  P'  =  Px  and  Py); 

substituting  for  P'  its  expression  from 

p  _i_  p/ 

^^  -  X  B  =  W, 

y==r(p  +  4W_2p)^  (p    ,   2W       ^1B 


B  B  'J3' 

solving  for  P, 

P  =  ~B~          B2 


STRUCTURAL  TYPES 


p  =  w  +  6W.b?  assigning  to  "  b  "  a  value  of  0.1  B, 
B  B2 

B  =  W  , 


173 


p  =  and  placing  this  in  - 

B  2 

P'  =  ,  which  are  the  expressions  for  the  maximum  and 

B 

minimum  pressure  ordinates  in  the  reaction  trapezoid  on  the  base  of 
structure  or  on  any  horizontal  plane  of  the  structure,  W  representing  the 
superposed  weight.  When  b  is  a  function  of  the  locus  of  resultant  of 
total  pressures  against  the  structure,  P,  P',  etc.,  are  expressions  of  total 
pressures  due  to  structure's  weight  and  of  pressure  moment  of  water 
column  restrained  by  the  structure. 


Fig.  36 


i 

H.E.P.93 
H.V.S. 


Fig.  37 


H.E.P.94 
H.V.S. 


From  Fig.  37  it  is  evident  that  the  distance  between  the  locus  of 
resultant  and  the  centre  of  the  base,  "b",  controls  the  distribution  of 
the  pressure. 


When  b  is  =        P  = 

o  B 


and  P'  =  zero, 


the  pressure  distribution  is  then  represented  by  the  triangle  e  f  j  and  the 
maximum,  P,  is  double  the  mean  pressure.  This  condition  represents 
the  limit  within  which  the  pressure  strains  are  met  by  compression  in 
the  structure;  any  further  moving  of  O  from  the  centre  of  the  base,  or 

r> 

any  increase  of  b  beyond  -,  creates  tension  in  the  superstructure. 


174 


HYDRO-ELECTRIC   PRACTICE 


Fig.  38 


T> 

In  Fig.  38  b  exceeds  --,  the  reaction  forces  are  represented  by  a 

positive  and  negative  triangle,  the  latter  represents  tension  developed 
at  the  base  of  the  structure,  by  which  the  pressure  theories  heretofore 
discussed  undergo  a  complete  change. 

T> 

This  condition  prevails,  therefore,  whenever  b  exceeds  — ,  and  the 

6 

structure  may  then  be  ruptured  in  the  portion  where  tension  stresses  are 
developed.  Safety  against  crushing  must  therefore  be  secured  by  so 
proportioning  the  section  that  the  maximum  pressure  P  is  within  the 

limits  of  the  strength  of  the  material, 
while  the  pressure  resultant  R  must  fall 
in  the  middle  third  of  any  horizontal 
joint  and  of  the  base. 

Upon  these  theories  the  spillway  de- 
sign must  be  based,  the  desideratum 
being  the  most  economical  section  in 
area  which  meets  the  requirements,  guar- 
anteeing stability  of  position  and  safety 
of  structure,  which  practically  resolves 
itself  into  obtaining  a  value  for  M  W 
which  exceeds  M  P  by  some  margin 
called  the  safety  factor,  S  f. 

ARTICLE  63. — What  a  safety  factor  should  be  must  be  decided  for 
each  case  from  those  conditions  which  are  likely  to  become  important 
factors  in  developing  the  resistance  capacity  of  the  structure  and  those 
which  may  tax  it. 

The  character  of  the  foundation  is  one  of  these  important  elements, 
no  matter  what  the  spillway  section  is.  It  will  be  appreciated  from  the 
presentation  of  the  stability  theories  that,  with  a  foundation  lacking  in 
rigidity,  several  of  the  important  theoretical  deductions  become  unreli- 
able in  fact,  as  stated;  preventing  water  from  entering  beneath  structure 
and  placing  it  on  an  unyielding  mass  are  essential  in  theorizing  from 
causes  to  effects. 

When  set  upon  a  hard  rock  ledge  and  securely  keyed  into  it,  the 
structure  may  be  regarded  as  having  become  a  part  of  it,  and  it  will 
develop  its  resistances  to  the  fullest  capacity.  This  cannot  be  expected 
in  alluvial  locations ;  water  penetration  can  be  guarded  against  efficiently 


H.E.P.95 
H.v.S. 


STRUCTURAL   TYPES  175 

by  proper  cut-off  construction,  and  rigidity  may  be  obtained  by  a  cor- 
rectly planned  pile-bearing  foundation;  but,  after  all,  the  responsibility 
is  merely  transferred  to  the  substance  in  which  the  piles  stand.  In  one 
case  in  the  author's  experience  the  underlying  material,  to  the  depth  of 
fifty  feet,  consisting  of  clay  and  sand,  bodily  moved  several  inches  down- 
stream; these  conditions,  therefore,  when  compared  with  rock  location, 
call  for  fundamental  increase  of  obtainable  safety. 

The  abutments  may  enhance  the  spillway's  resistance;  when  these 
are  natural  rock  banks,  the  structure,  unless  of  considerable  length, 
gains  from  them  greater  security  than  from  abutments  constructed  in 
or  against  alluvial  banks,  not  merely  because  there  is  less  possibility 
of  water  finding  a  way  around  them,  which  should  be  absolutely  guarded 
against,  but  because  of  the  rigidity  afforded  by  the  natural  bulwarks. 

The  height  of  overflow  is  an  important  condition;  though  fully 
credited  in  the  respective  design  in  accord  with  sound  theory,  it  is  never- 
theless obvious  that  the  larger  the  natural  forces  the  greater  the  possi- 
bilities of  failures.  In  general  high  overfalls  are  best  avoided,  but,  where 
they  must  be  reckoned  with,  the  safety  factor  should  be  prudently  adapted. 

Prevalence  of  trees  and  logs  passing  over  spillway  must  be  met  by 
an  increase  in  section  over  that  normally  required.  In  northern  latitudes 
heavy  ice  is  likely  to  form  and  subject  the  structure  to  abnormal  thrust 
which  finds  no  proper  resistance  factor  in  the  theoretical  design,  or  ice 
may  gorge  upstream  of  the  spillway  during  the  spring  break-up,  as  occurred 
during  the  last  winter  in  the  Alleghany  and  Monongahela  rivers  and 
brought  destruction  to  several  dams. 

And  finally  the  height  of  the  spillway  itself  has  a  most  important 
place  in  this  category.  High  dams  have  been  constructed  a  century  or 
more;  not  so,  however,  with  spillways;  designing  a  structure  a  hundred 
feet  or  higher  over  which  large  volumes  of  water  are  pouring  with  conse- 
quential shocks  of  the  leap  of  a  Niagara  is  quite  a  problem  apart  from 
that  of  a  dam  of  similar  height  restraining  a  pond  of  quiet  water.  It 
would  be  a  serious  fallacy  to  lay  down  a  rule  of  designing  spillways  of 
any  and  all  heights  with  a  fixed  safety  factor  of  two  or  whatever  measure. 

It  is  a  good  enough  business  axiom  to  apportion  the  insurance  to 
the  probable  loss,  and  this  has  its  place  here;  when  the  failure  of  a  spill- 
way is  likely  to  work  great  destruction  to  property  and,  perhaps,  of 
human  life,  the  possibility  of  such  a  happening  should  be  considered 
sufficient  reason  for  an  increase  of  the  safety  factor. 


176  HYDRO-ELECTRIC   PRACTICE 

The  following  is  suggested  as  a  basis  for  determination  of  the  safety  factor: 

1.  For  spillways  founded  on  rock  ledge  with  natural  rock  abutments S  f  =  2.00 

2.  For  spillways  founded  on  rock  ledge  with  constructed  abutments S  f  =  2.25 

3.  For  spillways  founded  on  alluvial  material  with  constructed  abutments  ...   S  f  =  2.50 

4.  For  overfall  in  excess  of  0.20  of  spillway  height  add  per  foot  of  such  excess  to  above  0.10 

5.  For  each  five  feet  of  height  of  spillway  in  excess  of  50  feet  add  to  above 0.10 

6.  When  failure  would  cause  great  destruction  add  to  above 0.25 

Example. — For  a  spillway  40  feet  high,  founded  on  alluvial  material, 
with  maximum  overfall  of  10  feet,  and  not  in  close  proximity  (5  miles) 
to  any  settlement,  the  safety  factor  should  be  taken  at  2.5  +  0.2  =  2.70, 
or  a  spillway  65  feet  high,  on  rock  bed,  with  constructed  abutments 
and  a  maximum  overfall  of  8  feet,  should  be  designed  with  a  safety 
factor  of  2.25  +  0.30  =  2.55. 

ARTICLE  64. — Having  determined  the  height  of  the  spillway,  the 
maximum  overfall,  and  the  safety  factor,  the  theoretical  design  is  worked 
out,  and  by  rinding  the  smallest  section  in  area  in  which  the  resultant 
falls  in  the  middle  third  of  the  base  and  M  W  =  M  P  X  S  f,  the  other 
stability  requirements  will  be  satisfied  until  certain  limits  of  height  are 
reached,  as  will  appear  in  the  further  discussion. 

Fig.  39  represents  sections  of  an  equilateral  triangle,  the  perpendic- 
ular being  the  upstream  or  pressed  surface:  condition  1,  without  water 
pressure, — i.e.,  when  the  pond  above  the  spillway  is  drawn  down;  condi- 
tion 2,  when  the  water  stands  at  the  top,  representative  of  the  low  stage, 
all  the  flow  being  diverted  to  the  power  station;  condition  3,  with  normal 
overflow;  and  condition  4,  with  highest  overflow  under  which  the  sta- 
bility requirements  are  satisfied.  The  sections  are  15  feet  high;  their 
material  weight  is  taken  at  140  pounds  per  cubic  foot;  the  areas  contain 
112.5  square  feet;  the  weights  are  expressed  in  short  tons,  the  pressure 
ordinates  in  pounds. 

T> 

Sec.       I.     No  water  pressure,  W  =  7.875,  b  =  2.5  =     ,  max.  pressure  on 

6 

the  base  —  2100  Ibs.  at  the  upstream  end. 
Sec.     II.     Water  at  the  top  of  the  section,  M  W  =  78.75,  M  P  =  17.5, 

b  =  0.28;   the  max.  pressure  on  the  base  =  1274  Ibs. 

Sec.  III.     Water  stands  3.75  feet  over  the  section,  M  W  =  78.75, 

M  P  —  31.6,  b  =  1.5,  the  max.  pressure  on  the  base  =  1940  Ibs. 
Sec.  IV.      The  water  stands  6.5  feet  over  the  section,  M  W       =  78.75, 

M  P  =  40.0,  b  =  2.5  =  ?,  max.  pressure  on  the  base  =  2800  Ibs. 
6 


MW=  78.75 
MP  =17.50 


MW=78.75 
MP=  40.00 


178  HYDRO-ELECTRIC   PRACTICE 

These  are  representative  of  the  fluctuating  forces  to  which  a  spill- 
way structure  is  exposed,  from  the  dry  pond  to  the  maximum  overflow 
condition,  and  the  reaction  diagrams  illustrate  the  shifting  of  the  pres- 
sures on  the  base  from  the  upstream  to  the  downstream  end,  being  a 
forcible  reminder  of  the  necessity  of  rigidity  in  the  foundation  and 
correct  analysis  of  the  pressures  for  the  overflow  conditions;  any  rise 
above  6.5  feet  will  develop  tension  at  the  upstream  end  of  the  base  and 
the  structure  will  become  unsafe. 

Fig.  40  presents  the  same  triangular  sections  as  in  Fig.  39,  but  in 
this  case  the  hypothenuse  is  the  pressed  surface. 

Sec.     V.     No  water  pressure,  W  =  7.875,  max.  pressure  =  2100; 

Sec.  VI.     The  water  stands  at  the  top  of  the  section 

P  =  5,     h  P  and  v  P  =  3.5,  W  is  composed  of 

AW  =  7.875  +  vP  =  11.375 

M  Wis  made  up  of  A  W  I/  =  39.375  +  v  P  L"  =  74.375 

M  P  is  made  up  of  H  P  L'  =  3.5  X  5  as  in  sec.  II  =  17.5 

R'  resultant  of  P  and  W     =  5  and  7.875  =  12 

T> 

b   =  2.5  =  —  and  max.  pressure  =1.6  tons. 

From  this  it  is  evident  that  this  section  will  not  meet  the  require- 
ments that  R'  fall  in  the  middle  third  when  water  stands  above  it,  as 
tension  will  be  developed  at  the  base  and,  though  stability  of  position 
is  amply  safeguarded  by  a  large  safety  factor,  the  structure  will  be  en- 
dangered by  reason  of  the  tension  stresses  developed  at  the  upstream 
end  of  base.  Note  that  v  P  does  not  enter  R',  which  represents  the  total 
pressure  resultant,  but  that  it  is  a  component  of  M  W,  as  M  P  contains 
h  P  only;  also  that  the  pressure  on  the  upstream  end  of  the  base  is  zero, 
with  and  without  water  pressure,  because  of  the  influence  of  v  P  in  the 
latter  case.  The  maximum  pressure  is,  of  course,  increased  under  water 
pressure. 

Sec.  VII,  Fig.  40,  is  a  rectangle  of  the  same  area  as  the  previous  sections; 

its  height  is  15  ft.,  the  base  7.5  ft. 
Water  stands  at  its  top,  M  W  =  29.5,  M  P  =  17.5,  b  =  2.22  and 

the  max.  pressure  3.17  tons  with  negative  pressure  of  0.77  ton 

at  the  upstream  end. 
This   section   is   apparently    unstable   for    any  water  pressure 

condition. 


Fig.  40 


MW=74.4 
MP  =  17.5 


H.E.P.97 
H.V.S. 

179 


180  HYDRO-ELECTRIC   PRACTICE 

ARTICLE  65. — The  practical  design  of  a  solid  spillway  must  conform 
to  other  conditions  aside  from  those  of  stability  considerations. 

The  top  of  the  structure  will  be  exposed  to  shocks  from  waves,  logs, 
and  ice,  and  must  be  given  commensurate  thickness;  the  overflowing 
water  will  plunge  vertically  on  the  downstream  face  of  the  spillway  and 
on  the  river  bed  below  unless  that  side  is  so  formed  that  the  volume  of 
maximum  overflow  follows  the  spillway  face  and  is  guided  in  a  direction 
by  which  the  river  bed  will  be  protected  against  the  water's  force.  The 
shocks  against  the  spillway  top  will  be  most  frequent  when  the  overflow 
is  shallow,  then  logs  and  ice  hit  the  structure  before  clearing  it;  under 
these  conditions,  however,  the  velocity  of  the  approaching  water  is  low 
and  these  shocks  are  comparatively  light.  When  the  river  is  in  flood,  the 
overflow  depth  is  correspondingly  great  and  most  of  the  floatage  then 
clears  the  crest  without  touching  it ;  the  velocity  of  the  water  is,  however, 
high,  and  if  floatage  then  strikes  the  top  the  shock  would  represent  great 
force.  This  would  be  the  case  when  bridges,  boat  landings,  and  build- 
ings are  carried  away,  or  large  trees  are  precipitated  with  the  caving 
banks  into  the  stream;  or  when  log  and  ice  jams  break  loose  and  are 
hurled  in  large  masses  against  the  structure.  The  force  of  such  shocks 
cannot  be  estimated,  nor  can  the  probability  of  such  occurrences  be 
ignored,  and  it  is  proper  to  take  account  of  these  possibilities  when 
designing  the  spillway. 

In  practice  reservoir  dams  are  given  a  top  width  of  one-tenth  of 
their  height,  and  that  of  spillways,  generally  speaking,  should  be  twice 
this, — i.e.,  the  top  width  of  the  spillway  should  be  two- tenths  of  the 
height  of  the  spillway. 

The  investigation  is  now  confined  to  the  designing  of  the  minimum 
area  section  in  which 

1.  The  pressed  surface  is  vertical; 

2.  The  top  width  equals  two-tenths  of  the  section  height; 

3.  The  downstream  face  is  inclined  to  receive  and  guide  the  overfall; 

4.  The  safety  factor  against  overturning,  with  maximum  overflow, 

exceeds  two; 

5.  The  locus  of  the  resultant  of  pressures  falls  into  the  middle  third 

of  the  section  base;  and 

6.  The  maximum  pressures  do  not  exceed  the  safe  strength  of  the 

material,  which  will  be  taken  at  ten  tons  per  square  foot. 


STRUCTURAL   TYPES  181 

A  trapezoid  represents  this  section,  which  will  hereafter  be  referred  to 
as  "the  normal  solid  spillway  section,"  and  its  proportions  of  design  are: 

Crest  width  equals  two-tenths  of  height; 

Base  length  equals  eight-tenths  of  height; 

Upstream  face  is  vertical; 

Downstream  side  is  inclined  one  vertical  in  0.6  horizontal;     : 

Structure  is  of  cyclopean,  monolithic,  or  block  concrete. 

Fig.  41.— Spillway  height S  =     15  feet 

Crest  width C  =      3  feet 

Base  length B  =     12  feet 

Spillway  area,  section A  =  112.5  square  feet. 

In  sec.  I  the  upper  pool  is  dry;  stability  against  crushing  is  the 
only  requirement  to  be  met.  The  pressures  are  represented  by  the 
weight  of  the  structure,  which  is  taken  at  140  pounds  per  cubic  foot; 

AW  =  112.5  X  140  =  15,750  Ibs. 

The  locus  of  the  pressure  line  in  the  base,  b,  is  found  from  the 
height  of  the  horizontal  gravity  plane 

G  C  =  ^4,-  X  |  =  0.4  S  =  6  feet, 
and  the  length  of  the  horizontal  gravity  plane 

g  p  =  x  +  c  =  o.; 

then 

T)  __  T>  "D  •»-* 

c\  c\  C\ 

Maximum  pressure 

p^     .R       6_Rb_ .  15750   ,    170100  _       LQQ  « 

-L     X.     ~~~     _  „     "T"  ~T  -.  ~~~~     ^  A«yO    IDfe* 

B          B-  12 


182  HYDRO-ELECTRIC   PRACTICE 

In  sec.  II,  Fig.  41,  the  water  stands  level  with  the  spillway  crest; 
all  characteristics  are  as  in  sec.  I,  and  H  =  15  feet. 

Water  pressure  P  =  31.25  H2  7031  Ibs. 

q 

Its  lever  arm  I/  =  -  5  ft. 

o 

Pressure  moment  M  P  =  7031  X  5  =    35,155  ft.  Ibs. 

Spillway  weight  W  =  112.5  X  140  =    15,750  Ibs. 

Its  lever  arm  L  =  B  —  g  P  =          7.8  ft. 

2 

Weight  moment  M  W  =  15,750  X  7.8  =  122,850  ft.  Ibs. 

Sliding  safety  factor  S  s  f  =  15,750  •*-  7031  =  2.24 

Overturning  safety  factor   Osf  =  122,850  -*-  35,155  =  3.5 

Pressure  resultant  R  =  J3.5*  +  7.875*  =  8.6  tons. 

Locus  of  R  in  base  b  =  0.5  g  p  +  O  R  -  0.5  B  =  0.43 

Resultant  falls  in  the  middle  third. 

Maximum  pressure  P  x  =  1790  Ibs. 

Minimum  pressure  P  y  =  1070  Ibs. 

In  sec.  Ill,  Fig.  41,  the  water  stands  3  feet  above  the  spillway  crest; 
characteristics  are  as  in  sec.  2  excepting  H  and  h 

H  =  18  feet     h  =  3  feet 

P  =    9,843  Ibs.,   L'  =  5.713    M  P  =    56,243  ft.  Ibs. 
W  =  15,750  Ibs.,    L   =  7.8      M  W  =  122,859  ft.  Ibs. 
Ssf=1.6  Osf  =  2.18 

R  =  9.27     tons      b  =  1.77      P  x  =  2,905  Ibs. 

All  the  requirements  are  met  by  this  section  for  a  spillway  of  any 
height  up  to  one  hundred  feet,  provided  the  following  conditions  are 
complied  with: 

(a)  the  structure  is  properly  founded  and  supported; 

(b)  protection  against  underwash  is  effective; 

(c)  the  spillway  consists  of  a  homogeneous  mass  of  concrete; 

(d)  the  maximum  overflow  does  not  exceed  two-tenths  of  the  height 

of  the  spillway. 

The  normal  section  may  be  adapted  to  abnormal  overflow  by  adding, 
for  each  foot  of  overflow  in  excess  of  the  normal,  a  rectangular  section 
half  a  foot  wide  to  the  normal  section;  and  by  reducing  the  normal 
section  by  a  similar  rectangle  for  each  foot  decrease  of  overfall  from 
the  normal. 


Normal    Solid 
Spillway  Section 


184  HYDRO-ELECTRIC   PRACTICE 

The  overturning  safety  factor  may  be  increased,  from  the  normal, 
by  the  addition  of  a  rectangle  half  a  foot  wide  for  each  one-tenth  increase 
of  such  safety  factor. 

Deductions  and  Tabulation  of  Dimensions,  Weights,  and  Characteristics 
of  the  NORMAL  SOLID  SPILLWAY  SECTION.  —  These  expressions  are  to  serve 
for  the  designing  of  CONCRETE  spillways  to  the  limit  of  100  feet  height; 
they  have  been  equated  for  the  two  fundamental  values,  height  of  spill- 
way and  of  overflow,  which  must  be  fixed  before  the  work  of  designing 
can  be  approached;  the  expressions  of  weights  are  in  specific  gravity  = 
140  -f-  62.5  =  2.24. 

A  =  B  +  C  X  S  =0.5  S2 

^ 

*W  =  2.24  A  =  1.12S2 

A,  =  EL±_h  x  g         =  i^_s  j-_q^s  x  s  =  07  s, 

2  — 

*  P  =  A'  =0.7  S' 


T,       H  +  2h       S 
H  +  h     S3 

1.2S  +  0.4SVS       1.6S' 
=  I^ST  072  S  X  3  =  4^S  ' 

_  6h  +Jh      5h     _  40h'  _ 

6h  +  h         3  21  h 

B  +  2CVS  .  0.8S+0.4S  XS..  04S 

"FTC^  X  3  "S  s  3  ' 

expressed  in  h  =  2  h 

g  p  =  0.56  S 
expressed  in  h  =  2.8  h 
L  =  B  -  0.5  g  p  =  0.8  S  -  0.28  S  =  0.52  S 
expressed  in  h  =  2.6  h 

*  M  P  =  LT  =  1.905  h  X  0.7  S2      =  1.33  h  S2 

*MW  =  LW  =  2.6  h  X  1.125  S2      =  2.93  h  S2 

*  Apply  multiplier  62.5  to  find  weight  in  Ibs. 


STRUCTURAL   TYPES  185 


*  R  =  ^  P  +  W*  =     0.7  S<  +  1.125  S<  =  1.325  S' 

g          PL'       B 
=  2  P       "W"     "  2 

=  0.28  S  +  '    -  0.4  S  =  0.118  S 


R  ,  6Rb_   1.325S'  ,  0.7  S  X  1.325S'_    o11c 
=  B  H      B^      ~08S~  ~  064^~ 

TABLE  10.—  CHARACTERISTICS  OF  THE  NORMAL  SOLID  SPILLWAY  SECTION. 

C  =  0.2S,  B  +  C  =  S,            h  =  C,  Osf  =  2.2 

tA  =  0.5S2  i  =  0.5S(S-n)  §  =  0.5S(S-fn) 

A'  =  0.7S2  =0.7S2-nS  =  0.7S2  +  nS 

W  =  1.12S2  =1.128  (S-n)  =1.128  (S+n) 
P  =  A' 

GC  =  2h  =  2(h  +  0.95n)  =2(h-0.95n) 

g  p  =  0.56  S  =  0.56  (S  -  0.8  n)  =  0.56  (S  +  0.8  n) 

L  =  2.6  h  =  2.6  (h  +  0.9  n)  =  2.6  (h  -  0.9  n) 

L'  =  1.905h  =  1.905  (h  +  0.9  n)  =  1.905  (h  -  0.9n) 
SSf  =  1.6 

S  f  =  2.18  to  increase  O  S  f  by  0.1  add  0.5  S  to  the  section. 

ARTICLE  66.  —  The  shaping  of  the  crest,  of  the  downstream  face,  and 
of  the  toe  of  the  spillway  are  the  remaining  features  to  complete  the 
practical  design. 

The  crest's  upstream  edge  should  be  slightly  rounded,  without, 
however,  giving  it  an  up-slope  of  any  length,  the  purpose  to  be  attained 
being  to  prevent  the  lodgement  on  or  against  it,  during  low  overflow,  of 
floatage;  the  square  edge  would  be  permissible  were  it  not  for  the  likeli- 
hood of  its  chipping  off. 

From  the  downstream  end  of  this  quarter-round  of  its  upstream 
edge  the  crest  should  be  inclined  downward  at  about  half  an  inch  per  foot. 

The  downstream  edge  of  the  crest  should  be  on  a  curve  of  a  radius 

2  C  2  C 

equal  to  —-J  the  point  of  curve  being  •—  from  the  upstream  face  plane, 
o  o 

and  the  point  of  the  tangent  in  a  horizontal  plane,  one  foot  below  crest 

*  Apply  multiplier  62.5  to  find  weight  in  Ibs. 

t  For  normal  overflow;  J  for  less  than  normal  overflow;  §  for  more  than  normal  overflow;  n  is 
feet  of  abnormal  overflow. 


186  HYDRO-ELECTRIC   PRACTICE 

point;  this  curve  will  be  slightly  fuller  than  the  parabola  of  the  upper 
film  of  the  overfalling  water,  the  purpose  being  to  secure  a  shape  of  crest 
to  which  the  falling  water  will  constantly  adhere  in  its  passage  over  it. 
The  same  argument  underlies  the  inclination  to  be  given  to  the  down- 
stream face,  a  condition  which,  as  will  be  seen,  is  fully  met  by  the  normal 
section. 

Fig.  42  shows  the  parabola  C  P  T  in  which  the  ordinates  m  a,  n  b, 
o  c,  etc.,  represent  the  velocity  of  the  water  V  =  ^/2g§h,  h  being  the 
height  of  overflow,  and  the  abscissae  m  m,  n  n,  o  o,  etc.,  the  fall  of  the 
water,  H  =  0.5  g  —  t2,  H  being  height  of  fall,  and  t  time  in  seconds;  from 
this  will  be  seen  that  the  downstream  incline  of  the  normal  section  prac- 

TT 

tically  parallels  the  parabolic  curve  up  to  a  point  Q  about  --  above  the 

base  when  the  produced  spillway  face  and  the  parabolic  curve  approach. 

This  is  the  point  from  which  the  downstream  face  tangent  should  be 

g 
changed  into  a  curve  of  a  radius  equal  o  forming  the  toe  of  the  spillway, 

£t 

the  latter  having  base  and  altitude  equal  to  0.1  B;  the  water  on  passing 
from  the  toe  has  assumed  a  horizontal  direction  and  its  force  is  spent 
upon  its  own  element. 

The  change  in  area  from  the  normal  section  due  to  the  shaping  of 
crest  and  of  the  toe  is  represented  by  the  addition  of  0.025  A  to  A. 

ARTICLE  67. — Gravity  spillways  are  types  in  which  the  vertical  com- 
ponent of  the  water  pressure  is  utilized  as  one  of  the  resistance  factors, 
the  upstream  face  being  inclined,  resembling  section  VI,  Fig.  38,  Art. 
64.  The  analysis  of  the  inclined  surface,  triangular  section,  has  shown 
that  it  lacks  in  stability  when  the  water  stands  at  the  top  of  the  section, 
because  the  gravity  line,  and  consequently  the  resultant,  falls  too  close 
to  the  turning  point,  and  this  can  be  overcome  only  by  the  addition,  to 
the  triangular  section  at  its  downstream  side,  of  a  rectangle,  by  which, 
however,  the  total  section  area  becomes  considerably  larger  than  that 
of  the  normal  solid  spillway  section.  For  this  reason  a  solid  section, 
with  an  upstream  inclined  face,  is  not  an  economical  design,  and  in  order 
to  take  advantage  of  the  vertical  pressure  factor  the  section  must  be 
designed,  in  part  at  least,  hollow. 

Timber  spillways  have  been  built  on  this  principle  for  many  years, 
the  upstream  face  being  inclined  45°  and  flatter,  but  were  confined  to 
low  structures  only;  the  development  of  reinforced  concrete  structures, 


C    m  _n      o P 4 r  _  s t__u___C* 

^ — -T. r — 4:-  — j * 1 13 


Fig.  42 

Solid  Spillway 
Crest  and  Toe 


H.E.P.99 
H.V.S. 


187 


188  HYDRO-ELECTRIC   PRACTICE 

however,  has  in  recent  years  broadened  the  practical  application  of  this 
principle  to  spillway  designs. 

Fig.  43  shows  a  triangular  section,  I,  with  its  upstream  surface  in- 
clined 45°,  to  which  is  added  a  rectangle,  II,  of  width  equal  to  the  height 
of  the  overflow,  and  to  this  a  downstream  triangular  section,  III,  of  such 
inclination  that  the  overfalling  water  will  adhere  to  it,  as  found  in  Article 
66,  Fig.  42. 

Height  of  section  ..........  S  =  15  feet 

Pressed  face  deck  ..........  D  =  S  %/2  =21.21  feet 

Top  or  crown  ..............  C  =  0.2  S  =     3  feet 

Downstream  side,  apron...  Ap  =  JS2  +  (0.6  S)2  =  17.5  feet 

Base  of  sec.  I  .............  B'  =  S  =15  feet 

Base  of  sec.  II  ............  B"  =  C  =    3  feet 

Base  of  sec.  Ill  ...........  B'"  =  0.6  S  =9  feet 

Total  base  ................  B  =  27  feet 

Overflow  ..................  h  =  0.2  S  =     3  feet 

Total  height  of  water  .......  H  =  1.2  S  =18  feet 

Pressure  /actors: 

A/       n  v  H  +  h  q  /2      1.2  S  +  0.2S 

Pressure  area  .............  A'  ••  —  -  —  •   fe  v  ^  X  —     —  -  — 

=  0.7S2\/2  225  sq.  ft. 

Pressure  ..................  P  =  A'  X  62.5  =  14,062  Ibs. 

Horizontal  component  ofP         =hP  =  P-^\/2  =     9,500  Ibs. 

T,        H+2hvD/0 
Pressure  lever  arm  ........  I/  =  -  -  X  --  —  v  * 

n.  +  n          o 

1.2  S  +  0.4  S       S  v/2 
"  L2  S  +  0.2  S  3 


4.2  S 
Pressure  moment  .........  M  P  =  P  L'  =  54,283  ft.  pds. 

Resistance  factors: 

Assuming  D,  C,  Ap  to  be  a  concrete-steel  shell  one  foot  thick,  and 
omitting  for  the  present  the  weight  of  the  reinforcing  steel: 

Weight  of  D  is  Dw  =  21.21  X  140  =  2969  Ibs. 

Weight  of  C  is  Cw  =    3        X  140  =    420  Ibs. 

Weight  of  Ap  is  Apw  =  17.5     X  140  =  2450  Ibs.     =       5,839  Ibs. 

Lever  arm  of  D  is  DL  =  B  -  0.5  B'  =    19.5  feet 

Lever  arm  of  C  is  CL  =  0.5  B"  +  B'"  =    10.5  feet 

Lever  arm  of  Ap  is  ApL  =  0.5  B'"  =     4.5  feet 


STRUCTURAL   TYPES 


189 


Structure's  weight  moment  =  Dw  X  DL  +  Cw  X  CL  +  ApwXApL  =    75,530  ft.  pds. 

Vertical  water  pressure  =  hP  =  9500  Ibs.     = 

and  its  lever  arm  =  B  -  L"  =       21.37 

its  moment  =  vPL" 

Sliding  safety  factor,  SSf  =  W  +  vP  -=-  hP  1.6 

Overturning  safety  factor  =  WM  +  vPM  ^  hPM  =        5.2 

without  WM,  OSf  3.8 


203,015  ft.  pds. 


and  this  is  the  distinctive  principle  upon  which  gravity  spillway  designs 
are  based,  namely  the  ratio  of  L"  :  L',  21.375  -f-  5.625  =  3.8.  " 


Fig.  43 


H.E.P.100 
H.V.S. 


D' 


Fig.  44 


H.E.P.101 
H.V.S. 


Fig.  44,  Locus  of  Resultant.  —  The  height  of  the  statical  moment  G  C 
is  the  same  as  in  a  solid  body; 


GC  = 


8 


B  +  C 


?  9  Q         d 

Zi.A  \j    .,    \3 

28        3 


its  locus  is  in  mm',  connecting  the  bisects  of  B  and  C,  and  is  algebraic- 
ally determined  from 

DD'   :  Dg  =  D'E   :  gn 

Dg  =  S  -  GC  V2  =  0.634S  V2  =  13.44 

D'E  =  0.5B  -  0.5C  =  12 

DD'  =  D  =  21.21 

gn  =  13.44  X  12  H-  21.21  =    7.6 

gP  =  (gn  +  0.50)2  =  18.2 


190 


HYDRO-ELECTRIC    PRACTICE 


Fig.  45 


The  force  diagram  is  projected  by  producing  P  to  its  intersection 
with  the  gravity  line  at  M,  laying  off  MN  =  W,  and  completing  the 
parallelogram  MNOP,  in  which  the  diagonal  R  represents  the  resultant 
of  all  pressure  and  R'  its  locus  in  the  base.  Both  pressure  lines  PM  and 

R  cut  the  base  in  its  middle  third. 

Theoretically  this  gravity  section  is 
therefore  safe  of  position.  It  now  remains 
to  be  inquired  how  the  parts  of  the  struc- 
ture must  be  designed  to  meet  the  strains 
to  which  they  will  be  exposed.  The  up- 
stream face,  the  deck,  may  fail  under  the 
superimposed  weight  .of  the  water,  and  it 
must  be  divided  into  separate  spans,  fixed 
at  their  ends  to  suitable  supports,  when 
they  will  represent  the  conditions  of  a  uni- 
formly loaded  beam  secured  at  its  ends. 
The  bending  moment  on  the  centre  of  such  a  beam  is  expressed  by 

Mo  =  -  — ,  in  which  Q  is  the  product  of  pressure  per  foot  into  length 

of  span  in  feet,  1  is  the  length  of  span  in  inches.  The  pressures  due 
to  the  various  heights  of  the  water  at  different  points  on  the  deck  are 
shown  by  the  force  lines  Pb,  PC,  Pd,  etc.  on 

Fig.  45  Pb  at  the  crown  with  overflow  =  5  ft. 


=  bn  X  62.5  =    5  X  62.5 
=  ab  X  tan  a  X    62.5 


=  312.5,  also 


a  b  =  ^  b  n2  +  an2 

bn  =  an  =  5  ft. 


=  7.071 


ab  =  A(bn2)2     =  bnV2  =  5 
tan  a  =  b  m  -j-  ab 

b  m  =  b  n   =5,  tan  a  =  5-r-5V2  =  - 

62.5  tan  a  =  62.5  -  V  2  =  44.19 

Pb,  PC,  Pd,  etc.,  are  =  ab  +  7  ft.  sections  X  62.5  tan  a,  or 
Pb  =  (ab  +  7)    X  44.19 
PC  =  (ab  +  14)  X  44.19,  etc.,  as  per  Table  11, 


MOMENTS  FOR  SPANS 

1  OF 

Spillway 

Pi 

10ft. 

12ft. 

14ft. 

height. 

26.0 

31,200 

44,928 

61,152 

Crown 

51.8 

62,160 

89,510 

121,834 

5  feet 

77.6 

93,120 

134,092 

182,516 

10  feet 

103.4 

124,080 

178,676 

243,196 

15  feet 

129.1 

154,920 

223,084 

303,644 

20  feet 

154.9 

185,880 

267,668 

364,324 

25  feet 

180.7 

216,840 

312,250 

435,006 

30  feet 

206.5 

247,800 

356,832 

485,688 

35  feet 

232.2 

278,640 

401,242 

546,134 

40  feet 

258.0 

309,680 

445,824 

606,816 

45  feet 

283.8 

340,572 

490,406 

667,498 

50  feet 

309.6 

371,520 

534,989 

728,179 

55  feet 

335.3 

402,360 

579,398 

788,626 

60  feet 

STRUCTURAL   TYPES  191 

in  which  P  is  this  pressure  per  square  foot,  Pt  per  square  inch  of  one  ft. 
of  beam,  and  M  the  moment  of  external  forces,  heretofore  analyzed, 
expressed  for  beams  of  10,  12,  and  14  feet  spans. 

TABLE  11.— CONCRETE-STEEL  GRAVITY  SPILLWAYS;  OVERFLOW  =  5  FEET. 

Moments  of  Bending  Forces. 

a,  P 

b 312.5 

c 621.8 

d 931.1 

e 1240.4 

f 1549.7 

g 1859.0 

j 2163.3 

k 2477.6 

1 2788.9 

r 3096.2 

s 3405.5 

u 3714.8 

v 4024.1 

The  external  forces  must  be  met  by  the  ultimate  resistance  of  the 
material  of  which  the  beam  is  constructed,  which,  for  reinforced  concrete, 
is  expressed,  as  per  Article  53,  O,  by  Mo  =  5505  t2,  in  which  t  is  the 
thickness  of  the  beam  in  inches,  provided  the  area  of  the  imbedded 
steel,  per  foot  of  beam  width,  q  =  0.132  t. 

When  Mo  =  M,  the  conditions  represent  theoretical  equilibrium,  and, 
in  order  that  the  structure  may  be  safe,  Mo  should  be  greater  than  M  by 
a  safety  factor  of  not  less  than  "four."  To  determine  t,  the  thickness 
of  the  deck,  in  this  case,  for  example  at  point  Pb : 

M  =  for  10  ft.  span  62,160  inch  pds. 

4  M  =  248,640  =  5,505  t2 

t  =  ^ ^48,640^^^5505  =  6.72  inches,  and 

q  =  6.72  x  0.132  =  0.887  square  inch  steel 

These  values  for  t  and  q  at  points  in  the  deck,  designated  as  b,  c,  d,  e, 
etc.,  applying  to  different  heights  from  the  crown  downward,  are  given 
in  Table  12  for  10,  12,  and  14  feet  spans. 


192 


HYDRO-ELECTRIC   PRACTICE 


TABLE  12.—  CONCRETE-STEEL  GRAVITY  SPILLWAYS;  VALUES  OF  t  AND  q. 

Spillway 
height. 

Crown 
5  feet 
10  feet 
15  feet 
20  feet 
25  feet 
30  feet 
35  feet 
40  feet 
45  feet 
50  feet 
55  feet 
60  feet 

If  the  supports  of  the  deck  spans  take  the  form  of  partition  walls,  filling 
the  entire  space  of  the  interior  of  the  spillway  shell  as  shown  in  Fig.  46, 
and  are  properly  designed  to  take  up  and  transmit  the  stresses  to  the 
foundation,  as  per  section  on  Fig.  46,  the  quantities  of  the  concrete  and 
of  the.  reinforcing  steel  required  are  those  given  in  Table  13. 

The  partition  walls  may  be  constructed  of  x  concrete,  all  the  other 
parts  are  of  xx  concrete.  The  distribution  of  the  reinforcing  steel  is 
also  shown  in  Fig.  46. 

TABLE  13.—  CONCRETE-STEEL  GRAVITY  SPILLWAY;   MATERIAL  BILL  FOR  10  FEET  OF 
SPILLWAY  ACCORDING  TO  THE  DESIGN  PER  TABLE  12  AND  FIG.  46. 


>ans. 

10ft. 

t. 

q. 

b  

4.76 

0.628 

c  

6.72 

0.887 

d  

8.23 

1.086 

e  

9.49 

1.253 

f  

10.61 

1.400 

11.58 

1.529 

i.  . 

12.55 

1.657 

k  

13.42 

1.711 

1  

14.23 

1.878 

r  

15.01 

1.981 

s  

15.73 

2.076 

u  

16.43 

2.168 

v.  . 

.    17.10 

2.257 

12ft. 

t. 

q. 

5.71 

0.754 

8.07 

1.065 

9.87 

1.303 

11.39 

1.503 

12.73 

1.680 

13.95 

1.841 

15.06 

1.988 

16.12 

2.128 

17.08 

2.255 

18.00 

2.376 

18.88 

2.502 

19.72 

2.603 

20.52 

2.709 

14ft. 

t. 

q. 

6.67 

0.880 

9.41 

1.242 

11.52 

1.521 

13.29 

1.754 

14.85 

1.960 

16.27 

2.148 

17.78 

2.347 

18.79 

2.480 

19.92 

2.629 

21.00 

2.772 

22.02 

2.907 

23.00 

3.036 

23.94 

3.160 

Heieht.feet.  X  Concrete  : 

10  feet  span  :  cub.  yds.  1  ft.  rise. 

10  ............................  '7.2  1.00 

20  ...........................  17.2  2.09 

30  ...........................  38.1  3.25 

40  ...........................  70.6  2.90 

50  ...........................  99.5  4.25 

60  ...........................  142.0  ---- 

12  feet  span  : 

10  ...........................  6.9  0.97 

20  ...........................  16.6  2.11 

30  ...........................  37.7  3.24 

40  ...........................  70.1  2.89 

50  ...........................  99.0  3.58 

60  ...........................  134.8  ____ 

14  feet  span  : 

10  ...........................  6.5  1.12 

20  ...........................  17.7  2.14 

30  ...........................  39.1  3.21 

40  ...........................  71.2  2.59 

50  ...........................  97.1  3.31 

60...                                               .  130.2 


XX 

Concrete  : 

cub.  yds 

.     1  ft.  rise. 

8.0 

1.52 

23.2 

0.99 

33.1 

1.06 

43.7 

1.16 

55.3 

1.22 

67.5 

10.3 

1.43 

25.0 

1.12 

36.2 

1.07 

46.9 

1.10 

56.9 

1.13 

69.2 

10.8 

1.70 

17.8 

1.30 

40.8 

1.31 

53.9 

1.42 

68.1 

1.54 

83.5 

•  •  .   > 

Reinf.  Steel : 


Ibs. 
1,230 
2,690 
4,190 
6,050 
8,190 
10,340 

1,600 
2,990 
4,650 
6,760 
9,100 
11,660 

1,760 
3,430 
5,100 
7,370 
9,860 
12,520 


1  ft.  rise. 
146.2 
150 
186 
214 
215 


139 
166 
211 
234 
256 


166 
167 
227 
249 
266 


Fig.  46 
Gravity  Spillway 


Distribution  of  *//*/-///fia&. 


Partition  Supports 


193 


194  HYDRO-ELECTRIC   PRACTICE 

When  a  gravity  spillway  of  this  type  is  erected  on  a  hard  rock  bed, 
its  downstream  face,  the  apron,  need  not  be  carried  to  the  spillway  toe, 
but  may  be  shortened  one-third  or  one-half,  the  chief  consideration  being 
whether  the  vertical  fall  of  the  water,  passing  over  the  spillway,  from  the 
end  of  the  foreshortened  apron  face,  will  cause  erosion  of  the  bed  rock  and 
thereby  weaken  the  structure's  footing.  A  partial  apron  design  is  shown 
in  Fig.  46;  the  reduction  in  material  for  this  type,  as  compared  with 
quantities  in  Table  13,  consists  of  about  4  cubic  yards  of  xx  concrete 
and  600  pounds  of  steel  for  10  feet  of  structure. 

TABLE  14.— CHARACTERISTICS  OF  THE  CONCRETE-STEEL  GRAVITY  SPILLWAY. 

Deck,       D  =  S  V2  =  1.414  S. 

Crown,     C  =  5  feet  =  5  feet. 

Apron,  Ap  =  S  V1.36  =  1.166  S. 

Base,        B  =  S  +  C  +  0.6  S  =  1.6  S  +  5. 

Crown  is  3  feet  thick. 
Apron  is  1  foot  thick. 
Partitions,  from  top  down  for  each  ten  feet  height,  are  respectively  12,  14,  16,  18,  21,  and 

24  inches  thick. 

Thickness  of  deck  is  as  per  Table  12. 
Steel  in  deck  is  as  per  Table  12. 

Steel  in  crown,  apron,  and  partitions  is  as  per  Fig.  46. 
The  form  of  the  crown  and  of  the  apron  toe  are  in  accordance  with  the  theory  presented 

for  solid  spillways  in  Article  66. 

ARTICLE  68.  The  Open  Spillway. — The  overflow,  as  has  been  noted, 
is  an  important  factor  in  determining  the  spillway  section,  one  of  its 
influences  being  to  increase  it  in  area,  while  the  ever-present  possibility 
of  the  exposure  of  the  spillway  to  fluctuating  pressure  strains  from  this 
source  is,  broadly  speaking,  an  undesirable  condition.  Failures  of  spill- 
ways, in  the  majority  of  cases,  can  be  traced  to  excessive  overflow;  any 
arrangement,  therefore,  which  allows  of  some  control  of  the  overflow  and 
thereby  reduces  the  pressure  fluctuations  is  a  very  desirable  one. 

When  the  rise  in  the  upper  pool  level  becomes  of  practical  utility 
as  a  power  function  by  offsetting  a  corresponding  rise  of  the  lower  level, 
thus  maintaining  a  constant  power  head,  this  condition  must  be  consid- 
ered in  arranging  for  the  permanent  lowering  of  the  overflow. 

If  some  of  the  upper  portion  of  the  spillway  were  removed  at  the 
approach  of  the  high  water,  the  excess  flow  could  be  passed  inside  of  the 
spillway  height,  or  nearly  so,  and  the  section  would  not  have  to  be  de- 
signed for  the  excessive  overflow  height;  furthermore,  the  lowering  of  the 


STRUCTURAL   TYPES 


195 


Fig.  47 
Overflow  Sluice 


H.E.P.104 
H.V.S. 


overflow  height  would  materially  reduce  the  upper  pool  flowage  area,  which 
will  represent  an  appreciable  economy  in  the  cost  of  the  development. 

The  effect  upon  the  overflow  by  the  lowering  of  a  portion  of  the 
spillway    appears   from    the 
following  example. 

Given  a  spillway  200  ft. 
long  and  30  feet  high,  the 
normal  or  power  flow  is  2000 
cubic  second  feet  and  the 
flood  discharge  10,000  sec. 
ft.;  therefore  the  maximum 
volume  which  passes  over 
the  spillway  is  8000  sec.  ft., 
and  the  overflow  is  5.2  feet. 

The  discharge  through  a  rectangular  opening  at  the  spillway  top, 
Fig.  47,  is  Q  =  0.62  CA^2gh,  where  C  is  a  coefficient  =  0.60,  A  the 
area  of  the  opening  in  square  feet,  h  the  height  of  the  water  above  the 
sill  of  the  opening. 

If  h  =  16  ft., 
Q  =  3  A  V16  =  12  A. 
A  =  8000  -5-  12  =  667  sq.  ft. 

Therefore  an  opening  of  about 
42  feet  length  and  16  feet 
height  or  two  openings  each 
22  feet  long  and  16  feet  high 
would  discharge  the  flood 
flow,  practically  none  passing 
over  the  spillway  crest,  and 
if  these  openings  are  closed 
during  the  normal  flow  periods 
the  required  power  head  may 
be  constantly  maintained. 
If  openings  are  made  near  the  base  of  the  same  spillway  the  discharge 
through  them,  Fig.  48,  is  Q  =  C  A  ^/  2  g  h,  where  C  is  a  coefficient  of  dis- 
charge through  a  submerged  orifice,  A  is  the  area  of  the  opening  in 
square  feet,  and  h  is  the  height  of  the  water  surface  above  the  centre 
of  gravity  of  the  opening.  For  this  purpose  C  is  taken  at  0.75. 


Fig.  48 
Underflow  Sluice 


196  HYDRO-ELECTRIC   PRACTICE 

If  the  opening  is  6  feet  high,  the  head  h  =  27  feet  measured  from 
the  crest  of  the  spillway  and  Q  =  6AJ27  =  31. 2  A 

A  =  8000  -5-  31.2  =  256.4, 

and  the  flood  volume  of  8000  sec.  ft.  would  be  discharged  through  five 
openings  each  9  feet  wide  and  6  feet  high.  The  theory  of  efflux  from 
orifices  is  developed  in  Article  74. 

This  is  the  theory  upon  which  the  design  of  the  open  spillway  is  based. 
The  devices  by  which  this  result  can  be  realized  may  be  classified  as 

(1)  Overflow  sluices,  being  separate  openings  in  the  top  of  the  spill- 
way; 

(2)  Underflow  sluices,  which  are  similar  openings  at  the  base  of  the 
structure,  and 

(3)  Movable  weirs,  representing  continuous  openings  along  the  top 
of  the  spillway. 

Any  of  these  must  be  arranged  to  be  readily  opened  and  closed;  they 
should  form  a  water-tight  wall  of  safe  strength  when  closed,  be  simple 
of  construction  and  operation  and  economical  in  cost  and  maintenance. 

The  closing  devices  may  be  classified  as  stop-logs,  drop,  lift,  and 
revolving  gates,  vertical  and  horizontal  valves,  needles,  wickets,  shutters, 
and  bear-traps. 

Overflow  sluices,  Fig.  49,  are  formed  by  masonry  piers,  steel  or  timber 
trestles,  placed  upon  and  secured  to  the  body  of  the  spillway  structure; 
the  openings,  as  has  been  shown,  are  determined  by  the  volume  of  the 
water  to  be  discharged;  an  operating  platform  is  placed  upon  the  piers 
or  trestles.  The  sections  of  the  sluice  supports  are  so  designed  that  the 
pressures  and  bending  forces  against  the  closed  sluice  spans  and  against 
their  own  pressure  faces  are  safely  resisted;  lateral  pressures  need  not 
be  considered,  since  the  accumulation  of  pressure  heads  against  support 
sides  is  readily  avoided. 

Stop-logs,  Fig.  50,  may  be  employed  to  close  overflow  sluices;  they 
are  square  timbers  placed  horizontally  one  upon  another  in  the  sluice 
span,  their  ends  resting  against  shoulders  arranged  in  the  supports; 
they  are  operated  by  hand  or  mechanical  devices  from  the  operating 
platform,  and  can  readily  be  formed  into  a  water-tight  curtain. 


STRUCTURAL   TYPES 


197 


Needles,  Fig.  51,  are  stop-logs  placed  vertically  side  by  side,  footing 
against  a  sill  secured  in  the  sluice  bed,  and  supported  on  the  top  by 
horizontal  strain  members  or  the  platform.  They  are  not  as  readily 
manipulated  as  are  stop-logs  of  the  horizontal  type,  and  it  is  also  more 
difficult  to  make  them  water-tight. 


Fig.  51 
Needles 


H.E.P.108 
H.V.S. 


Valves,  Fig.  52,  are  timber  or  steel  framed  shutters  revolving  around 
vertical  or  horizontal  steel  shafts,  their  ends  set  in  side  supports  or  in 
sluice  bed  and  top  strain  member,  and  they  close  up  against  the  sluice 
supports  and  sill;  they  are  operated  by  hand  or  mechanically,  but  it 
is  difficult  to  prevent  leakage  along  their  sides  and  bottom. 


198 


HYDRO-ELECTRIC   PRACTICE 


Gates,  Fig.  53,  may  be  vertical  lift,  drop,  or  revolving;  they  are  of 
timber  or  steel  frames  and  sheeting  and  are  generally  operated  by  power. 
Lift  and  revolving  gates  must  remain  suspended  above  the  sluice  span 
when  open,  requiring  extra  high  supports,  or  they  may  be  lowered  into 
recesses  arranged  in  the  spillway  masonry;  in  the  first  case  they  are 
exposed  to  the  wind  pressure  and  the  supports  must  be  designed  in 
accordance;  in  the  latter  arrangement  the  recesses  in  the  spillway  are 

likely  to  be  filled  with  sand.  Gates  form 
effective  closing  devices  and  can  easily  be 
made  water-tight. 

Shutters,  Fig.  54,  are  constructed  of 
timber  or  steel  and  are  hinged  to  a  sill; 
they  may  also  be  arranged  to  operate 
automatically  by  folding  or  dividing  them 
into  two  or  more  parts  hinged  on  opposite 
sides  of  the  sluice  bed.  When  water  from 
a  higher  level  is  let  in  underneath  them, 
they  will  rise  in  "A"  shape,  and  may  be 
maintained  in  that  position  until  the  water 
is  withdrawn,  when  they  fall  down  on 
their  beds. 

Bear-traps  are  of  this  general  design. 
Underflow  sluices,  Fig.  55,  are  openings 
cut  out  of  the  spillway  body  near  its  base, 
and  may  be  of  rectangular,  square,  or 
circular  form;  they  may  be  closed  by  lift 
gates  or  valves  operated  from  above. 
Movable  weirs,  Fig.  56,  are  devices  filling  the  entire  top  of  the  spill- 
way or  the  greater  portion  of  it,  and  consist  of  separate  steel  trestles 
placed  transversely  of  the  spillway  and  hinged  to  the  sluice  base.  When 
down  they  lie  in  a  recess  formed  in  the  spillway  masonry ;  to  erect  them 
the  first  trestle  is  raised  to  a  vertical  position  by  means  of  chains  from 
the  abutment  or  pier  and  secured  by  some  automatic  locking  arrange- 
ment; after  placing  a  foot-bridge  from  this  first  trestle  to  the  abutment 
or  pier,  the  second  trestle  is  similarly  raised,  and  so  on.  Trestles  are 
spaced  from  8  to  16  ft.  centres  and  their  upstream  faces  are  covered  with 
needles.  They  may  be  lowered  in  the  same  manner  as  described  for  their 
raising.  Shutters  and  bear-traps  may  also  be  utilized  for  movable  weirs. 


STRUCTURAL  TYPES 


199 


The  results  aimed  at  with  the  open  spillway  type  are  to  afford 
ready  control  of  the  overflow,  to  maintain  the  power  head  as  constantly 
as  practicable,  and,  generally  speaking,  to  reduce  the  overflow  height, 
and  to  accomplish  all  this  without  any  waste  of  the  water  by  leakage. 
It  is  evident  that  the  ideal  flow  control  will  be  secured  when  the  over- 
flow height  is  reduced  by  horizontal  sections  of  the  smallest  areas;  sim- 
plicity and  economy  of  the  device  and  of  its  operation  are  of  like  impor- 


tance.  While  the  movable  weir  probably  represents  the  most  complete 
method  of  accomplishing  this,  it  is  also  among  the  most  costly  and 
complicated  and  cannot  readily  be  made  water-tight;  its  field  of  use- 
fulness is  rather  for  navigation  works  than  power  plants.  Both  the  over 
and  underflow  sluices  meet  the  requirements,  the  first  for  the  solid,  the 
latter  for  the  gravity  spillway. 

For  gravity  spillways  the  underflow  sluice  may  be  a  concrete  culvert 
or  a  steel  plate  pipe,  the  intake  being  fixed  in  the  deck,  the  sluice  passing 
through  the  spillway  along  its  base  and  terminating  at  the  apron  toe; 
the  flow  through  them  can  be  controlled  by  valves  operated  from  the 
interior  of  the  spillway.  In  solid  spillways  the  underflow  sluice  is  inaces- 
sible  and  weakens  the  structure  by  reducing  its  mass  at  the  point  where 
it  is  most  required. 


200 


HYDRO-ELECTRIC   PRACTICE 


The  overflow  sluice  forms  the  most  recommendable  type  of  the 
open  spillway,  and  its  closing  is  best  arranged  by  stop-logs. 

The  sluices  should  be  designed  of  rather  small  than  large  areas,  as 
the  narrower  spans  require  shorter  stop-logs  which  are  therefore  more 
readily  handled. 


Example. — The  flood  flow  is  3000  cub.  sec.  ft. ;  the  spillway  is  200  feet 
long  and  the  overflow  limit  2  feet.  The  spillway  discharge  aggregates 
1700,  and  the  balance  of  1300  cub.  sec.  ft.  is  to  be  passed  through 
overflow  sluices. 

The  overflow  sluice  area  required  to  discharge  1300  cub.  sec.  ft.  is 
from  Q  —  3 A  V  h  with  h  =  6,  a  =  180  (practically) . 

The  programme  is  to  divide  the  total 
sluice  length  of  30  feet  into  suitable  units 
which  will  be  taken  at  10  feet;  the  loca- 
tion of  these  three  sluices  should  preferably 
be  near  the  end  where  the  power  station 
is  situated,  without,  however,  interfering 
with  the  tail-race  outflow,  if  the  station  is 
near  the  spillway.  The  sluice  supports  are, 
most  economically,  concrete  piers  of  the 
same  section  as  that  of  the  spillway,  with 
shoulders  arranged  vertically  in  their  sides 
to  serve  as  stop-log  supports,  which  may 
be  as  close  to  -the  upstream  face  of  the  spillway  as  practicable.  The 
sluice  pier  then  becomes  a  section  of  the  upper  six  feet  of  the  spillway 
section,  at  the  base  of  which  the  length  of  the  horizontal  transverse  plane 


Fig.  55 

Underflow 

Sluice 


H.v.S. 


STRUCTURAL   TYPES  201 

is  9.6  feet,  this  becomes  the  base  of  the  sluice;  the  thickness  of  the  pier 
is  determined  from  the  pressures  and  bending  forces  against  the  sluice 
span  which  are  transmitted  to  the  pier  as  the  end  support  of  a  beam  of 
the  length  of  the  span. 

For  a  span  of  10  feet  length,  pressure  P  =  62  X  31.25  =  1125  Ibs., 
and  for  10  feet,  representing  one-half  of  the  two  adjacent  spans,  P  = 
11,258  Ibs.  For  a  pier  three  feet  wide,  the  pressure  per  foot  P  =  3750, 
to  which  is  added  the  pressure  against  the  pier  1125;  total  pressure 
against  one  foot  of  the  pier  =  4875  Ibs. 

The  depth  of  the  sluice  is  taken  at  6  feet  and  the 

piers  should  be  raised  about  2.5  feet  to  elevate 

the  operating  platform  to  a  safe  height.     The 

pier  becomes  8.5  feet  high  and  its  area =  59.5  sq.  feet. 

the  weight,  at  140  Ibs.  per  cub.  ft =  8330  Ibs. 

The  pressure  lever  arm =  2  ft., 

and  the  weight  lever  arm =  5.9  ft., 

Pressure  moment  is  9750  ft.  pds. 
Weight    moment  is  49147  ft.  pds. 

Sliding  safety  factor  =1.7 

Overturning  safety  factor =5 

The  bending  moment  at  end  supports  of  10  ft.  span    =  112,500  inch  pds. 

and   for   the   intermediate   pier   between   two 

sluices =  225,000  inch  pds., 

which    is    resisted   by    the    working   shearing 

strength  of  concrete  taken  at  75  Ibs.  per  square 

inch;  the  pier  required  therefore  is =21  square  feet; 

that  of  the  assumed  section  is =  28.8  square  feet. 

As  a  matter  of  fact,  no  economy  is  secured  in  this  case,  or  when  the 
required  sluice  length  is  only  a  small  portion  of  the  spillway  length,  by 
confining  the  thickness  of  the  piers  to  their  theoretical  design,  a  broader 
pier  can  be  constructed  for  less  cost  by  permitting  of  the  use  of  cyclopean 
concrete;  but  when  the  sluice  lengths  nearly  take  up  the  entire  spillway, 
as  may  be  the  case  when  the  spillway  occupies  a  narrow  gorge,  the  pier 
design  is  thus  determined. 

The  thickness  of  the  stop-logs  is  found  from  the  bending  moment  at 
the  centre  of  a  beam  supported  at  the  ends,  for  this  case,  and  the  lowest 
beam,  P  =  wh  =  62.5  X  6  -375.  The  bending  moment  M  =  PI2 12  -i-  8 


202 


HYDRO-ELECTRIC   PRACTICE 


=  375  X  102  X  1.5  =  56,250  inch  Ibs.  The  fibre  stress  of  pine  being  taken 
at  2000  Ibs.  per  square  inch,  M  =  Fbh2  -4-  6,  b  is  the  breadth  (12"),  h  the 
thickness,  therefore 


h  =  A/M  -7-  2  F  =  3.8  (appr.).     In  practice  the  log  is  6"  X  12". 

The  operating  platform  may  be  of  3-inch  planks  with  guard-rails; 
the  stop-logs  can  readily  be  raised  and  put  in  place  by  the  aid  of  hand 
tools  or  by  hand-power  winches. 


Fig.  56 
Movable  Weir 


H.E.P.113 
H.v& 


Plan 


These  represent,  in  the  author's  judgment,  the  three  important 
practical  spillway  types,  and  in  the  light  of  all  that  has  been  presented 
regarding  them  the  closing  consideration  can  now  be  approached. 

ARTICLE  69. — In  determining  the  spillway  type  to  be  adopted  for  any 
specific  case,  adaptability,  first  cost,  and  maintenance  are  the  weights, 
in  their  logical  sequence  of  importance,  to  be  applied  to  the  inquiry;  and 
the  conditions  which  must  guide  the  choice  to  one  of  these  three  as  the 
best  suited  are  the  character  of  the  river  bed,  the  height  of  the  spillway, 
and  the  flood  volume.  The  river-bed  formation  may,  for  this  purpose, 
be  classified  as  hard  and  soft,  rock  and  hard  alluvial  material  being 
embraced  in  the  first  and  all  other  alluvial  composition  under  the  second ; 
for  the  former  bearing  foundations  may  generally  not  be  required,  while 
they  are  essential  for  any  spillway  in  the  soft  locations.  The  spillway 


STRUCTURAL   TYPES  203 

height  and  consequential  weight  of  the  structure  may  have  some  influence, 
so  will  the  volume  of  flood  flow,  the  latter  especially  as  between  the  open 
spillway  and  the  other  types. 

Example  1. — A  30-feet-high  spillway,  200  feet  long,  is  to  be  erected 
in  a  rock  river  bed;  the  flood  flow  excess  over  the  power  volume  is  8000 
sec.  ft.  The  solid  type  is  adapted  to  these  conditions,  the  overflow  being 
5.2  ft.,  or  inside  of  the  normal  section  limit,  it  contains  3330  cub.  yds., 
and  may  be  constructed  of  cyclopean  concrete  in  which  the  ratio  of 
mans  tones  of  8  cub.  ft.  volume  to  concrete  is  about  1:3,  or  the  material 
consists  of  about  1110  cub.  yds.  of  manstones  and  2220  cub.  yds.  of  xx 
concrete.  Manstones,  if  delivered  at  site  for  $2.50  per  cub.  yd.,  may  be 
estimated  at  $3.50  per  cub.  yd.  in  place;  with  cement  delivered  at  $2.50 
per  bbl.,  sand  $1.00  per  cub.  yd.,  gravel  or  broken  stone  at  $0.75  per  cub. 
yd.,  forming  timber  at  $25.00  per  M  ft.  b.m.,  skilled  labor  $4.50  per 
day  and  common  labor  $0.20  per  hour,  xx  concrete  may  be  estimated 
at  $7.00  per  cub.  yd.  in  place. 

The  estimated  cost  of  the  spillway  superstructure  then  is 

for  1110  cub.  yds.  of  manstones  at  $3.50     $3,885 

2220  cub.  yds.  xx  concrete  at     7.00     15,540     $19,425, 

being  practically  $100  per  lin.  ft.  of  structure,  coffering,  preparing  bed 
and  foundation  not  being  included. 

The  gravity  spillway  of  the  design  given  in  Article  67  is  adapted  to 
these  conditions,  the  overflow  being  only  slightly  above  the  standard 
therein  fixed;  the  material  contained  in  it  for  12  ft.  deck  spans,  accord- 
ing to  the  design  of  Article  67,  consists  of 

763  cub.  yds.    x    concrete, 
724  cub.  yds.  xx  concrete 
93,000  Ibs.  reinf.  steel. 

At  the  same  unit  cost  of  material  and  labor  above  quoted, 

x  concrete  may  be  estimated  at   $10.00  per  cub.  yd.  in  place, 
xx  concrete  may  be  estimated  at     12.00  per  cub.  yd.  in  place,  and 
reinforced  steel  estimated  at  60.00  per  ton  of  2000  Ibs. 


204  HYDRO-ELECTRIC   PRACTICE 

The  estimate  for  the  gravity  spillway  will  then  be  for 

762  cub.  yds.    x  concrete  at  $10.00 $7,620.00 

724  cub.  yds.  xx  concrete  at     12.00 8,688.00 

46.5  tons  of  reinf.  steel  at         60.00 2,790.00 

$19^098.00 
or  practically  the  same  amount  as  the  estimate  for  the  solid  type. 

The  open  spillway  for  these  conditions  has  already  been  detailed, 
and  the  material  required  in  it  consists  of  that  given  for  the  solid  type 
less  the  quantities  represented  by  the  three  sluice  areas,  or  about  37 
cub.  yds.,  which,  being  divided  between  manstones  and  concrete  at  the 
stated  ratio,  makes  the  estimate 

1098  cub.  yds.  manstones,  $3.50  $  3,843.00 

2197  cub.  yds.  xx  concrete  7.00  15,397.00 

$19,222.00 
and  for  three  sets  of  stop-logs  and  the  operating  platform  250.00 

$19,472.00 
which  is  also  practically  the  same  estimate  as  the  former  two. 

The  maintenance  will  be  very  small,  if  any,  for  the  solid  and  the 
gravity  type,  and  only  that  for  the  renewals  of  stop-logs  in  the  open 
spillway.  Operating  charges  are  alike  for  the  first  two,  while  the  open 
spillway  calls  for  constant  attention,  which,  however,  when  the  power 
station  is  near  or  at  the  spillway,  can  readily  be  furnished  by  the  station 
personnel,  but  if  the  station  is  at  a  considerable  distance  from  the  spill- 
way, an  attendant  should  be  located  at  that  point. 

Summing  up  the  comparison  for  the  rock  location,  it  appears  that 
each  of  the  three  types  is  adapted  to  the  requirements,  that  the  first 
cost  of  all  three  differs  but  slightly,  and  that  neither  the  solid  nor  the 
gravity  type  involves  any  maintenance  or  operating  charges,  which, 
however,  is  the  case  with  the  open  spillway;  whether  the  advantage 
afforded  by  the  last  in  controlling  the  flood  flow,  reducing  the  flowage 
areas,  and  removing  one  of  the  most  common  causes  of  danger  to  spill- 
ways is  of  sufficient  weight  to  recommend  it  in  preference  to  the  others 
must  be  decided  largely  from  the  typical  conditions  of  the  case  to  be 
served.  In  this  connection  it  is  well  to  note  that  the  open  spillway 


STRUCTURAL   TYPES  205 

arrangement  affords  a  ready  opportunity  to  utilize  the  storage  capacity 
of  the  upper  pool  in  low-flow  periods  by  accumulating  water  during  the 
non-operating  period  of  the  plant. 

Example  2. — The  same  structure  is  to  be  erected  in  a  soft  alluvial 
location,  for  which  the  former  comparisons  will  prevail,  with  the  addition 
of  the  foundation  cost,  which  will  be  somewhat  higher  for  the  gravity 
type  than  for  either  of  the  other  two,  or  practically  in  ratio  to  the  width 
of  the  spillway  base,  which,  according  to  the  designs  herein  outlined,  is 
27  feet  for  the  solid  and  open  and  53  feet  for  the  gravity  spillway;  the 
cost  of  coffering  is  also  likely  to  be  greater  for  the  structure  with  wider 
foundation. 

Example  3. — When  the  height  of  the  spillway  exceeds  30  feet,  a 
new  element  enters  the  search  for  the  most  recommendable  type, — that 
is,  the  location  therein  of  the  power  equipment.  The  specific  treatment 
of  this  programme  will  be  found  in  the  description  of  power  stations  in 
Article  78;  suffice  it  to  state  here  that  for  such  spillway  requirements, 
in  connection  with  the  direct  development  programme,  the  arranging 
of  the  power  station  in  the  interior  of  a  gravity  spillway  is  perfectly 
practical,  and  represents  a  considerable  saving  in  the  first  cost  of  the 
plant  and,  in  addition,  secures  the  highest  obtainable  efficiency  from 
power  functions,  flow  and  fall. 

ARTICLE  70. — Timber  spillways  have  played  an  important  part  in 
the  mill-power  plants  of  the  past,  and,  while  the  advent  of  concrete 
construction  and  the  rapid  increase  of  the  cost  of  timber  have  well-nigh 
discontinued  their  use,  occasions  may  arise  where  they  deserve  consid- 
eration. For  low-fall  developments  in  localities  where  timber  is  plentiful 
while  concrete  material  is  not  so,  transportation  facilities  being  limited, 
this  type  may  prove  recommendable  because  a  masonry  or  concrete 
structure  would  be  prohibitive  in  cost.  The  chief  objections  to  timber 
spillways  are  the  difficulty  of  constructing  and  maintaining  them  water- 
tight and  the  cost  of  keeping  them  in  repair.  As  timber  is  preserved  best 
when  constantly  saturated,  it  would  be  preferable  if  water  passed  through 
and  over  such  a  spillway  at  all  times ;  but  when  the  conserving  of  all  the 
flow  for  power  purposes  is  a  fundamental  requirement  of  the  develop- 
ment programme,  as  will  often  be  the  case,  this  safeguard  against  early 
decay  of  the  timber  must  be  forfeited  and  the  limit  of  the  structure's 
endurance  becomes  a  factor  in  the  determination  of  its  availability, — 
that  is,  the  maintenance  cost  of  a  timber  spillway  should  be  taken  at 


206  HYDRO-ELECTRIC   PRACTICE 

not  less  than  five  per  cent,  per  annum  of  its  first  cost,  whereby  it  could 
be  practically  renewed  in  twenty  years. 

The  stability  of  timber  spillways  is  determined  in  like  manner  as 
of  the  types  heretofore  considered, — that  is,  sliding  and  overturning  must 
be  resisted  by  the  weight  of  the  material  with  which  the  framed  structure 
is  filled,  which  may  be  rock,  gravel,  or  sand,  a  mixture  of  the  latter  two 
being  preferable  because  it  represents  the  most  compact  mass.  The 
weight  of  such  a  fill  may  be  taken  at  about  94  pounds  per  cubic  foot,  or 
for  the  purpose  of  stability  discussion  at  1.5  that  of  water.  In  a  crib 
structure  of  8  feet  bays  the  ratio  of  timber  to  filled  area  is  about  as  1  to  4. 

The  design  of  the  timber  spillway  should  be  adapted  to  uniformity 
of  shaping  and  framing  the  material.  The  upstream  face  may  be  vertical 
or  inclined;  the  downstream  side  should  conform  to  the  inclination 
found  to  represent  closely  the  parabolic  curve  of  the  overfalling  water, 
but  for  structural  reason  it  is  best  formed  in  steps  of  short  threads  so 
that  floatage  will  not  strike  them;  the  rise  of  the  steps  should  be  of 
even  number  of  feet  to  facilitate  uniform  framing,  the  threads  should  be 
of  a  width  to  make  up  the  desired  slope. 

Fig.  57,  section  1,  suggests  a  timber  crib  spillway  design  in  which 
S  is  vertical,  B  =  1.5  S,  C  =  0.5  B,  and  the  stepping  is  arranged  to  form 
the  standard  overfall  slope 

S  =  20  ft.,  B  =  30  ft.,  C  =  15  ft., 

A  =  408  sq.  ft.,  mean  area  of  timber  per  lin.  ft.  =    86  sq.  ft., 

mean  area  of  fill  per  lin.  ft.  =  322  sq.  ft., 
P'  =  0.7  S2  X  62.5  =  17,500  Ibs., 
W  =  322      X  94     =  30,268  Ibs., 
SSF  =  1.7, 

L'  =  24  +  8  -s-  24  +  4  X  (20  -*-  3)  =  7.65, 
MP  =  17,500  X  7.65  =  133,875  Ibs. 

The  irregularity  of  the  timber  and  fill  distribution  renders  a  precise 
determination  of  L  impracticable ;  if  the  body  is  considered  as  of  a  homo- 
geneous mass,  the  form  being  transformed  into  a  rectangle  of  similar 
area,  or  20  feet  high  and  22.5  feet  long,  the  error  as  relating  to  L  will 
be  unimportant  and  on  the  side  of  safety;  or 

L  =  11.25,  M  W  =  340,515  ft.  Ibs.,  and  OSF  =  2.25. 


Fig.  57 
Timber  Spillways 

Sec.  I 


m 


H.E.P.114 
H.V.S. 


207 


OF  THE 

i  r-  r-t  e>  IT"  \/ 


208 


HYDRO-ELECTRIC   PRACTICE 


The  framing  is  shown  in  the  figure,  consisting  of  alternate  longi- 
tudinal and  transverse  square  timbers;  the  former  are  staggered  one 
above  another  excepting  in  the  upstream  face,  the  latter  are  placed  8 
feet  centres;  the  longitudinals  are  doubled  at  the  apron  end  and  are 
laid  close  in  the  top  streak  under  the  crown.  The  entire  structure  is 
covered  with  3-inch  planking,  to  make  it  as  water-tight  as  possible, 
prevent  the  washing  out  of  any  of  the  filling  material,  and  protect  the 
crib  timbers.  The  crown  is  given  a  slight  slope  to  prevent  the  lodgement 
of  floatage;  its  upstream  edge  is  rounded  and  sheeted  with  iron  plates. 

The  substructure  of  a  timber  spillway  is  of  the  same  type  as  for 
concrete  spillways,  consisting  of  the  cut-off,  the  bearing  piles,  if  the 
location  is  in  soft  material,  and  of  the  apron;  for  the  structural  type  of 
the  latter  heretofore  described,  a  rock-filled  trench  may  be  substituted, 
that  is  if  heavy  rock  is  available,  and  the  trench  should  be  not  less  than 
three  feet  deep,  and  its  width  should  be  equal  to  half  of  the  spillway 
height  in  order  to  insure  that  all  of  the  overfall  strikes  this  rock  fill.  A 
gravel  and  earth  fill  may  be  placed  against  the  upstream  side  of  the 
spillway,  but  it  should  not  be  expected  to  add  to  the  resistance  weight  of 
the  structure,  as  the  upstream  side  will  always  be  exposed  to  the  hydro- 
static head  of  its  full  height.  As  a  matter  of  fact,  this  upstream  side  will 
sooner  or  later  fill  in  from  the  sediment  and  silt  carried  by  the  stream. 


TABLE  15.— APPROXIMATE  QUANTITIES  OF  THE  MATERIAL  REQUIRED  FOR  TIMBER 
SPILLWAYS  OF  THE  DESIGN  HERE  DESCRIBED  IN  LENGTHS  OF  EIGHT  FEET  AND 
FOR  VARYING  HEIGHTS. 


12  X  12 

timbers, 

Height.  ft.  b.m. 

10 3,000 

12 3,800 

14 4,700 

16 5,800 

18 7,000 

20 8,300 

22 9,700 

24 11,000 

26 12,300 

28 13,700 

30 15,000 

32 16,400 

34 17,800 

36 '. ..  19,200 

38 20,600 

40 22,000 


Wrought 
iron  drifts, 
Ibs. 

3X  12 
planking, 
ft.  b.m. 

250 

900 

300 

1,050 

355 

1,200 

410 
475 

1,350 
1,500 

545 

1,650 

620 
700 

785 

1,800 
1,970 
2,150 

875 
965 

2,300 
2,500 

1,060 
1,160 

2,700 
2,900 

1,265 
1,375 

3,100 
3,300 

1,500 

3,500 

Spikes, 

Ibs. 

430 

500 

570 

640 

710 

780 

860 

940 

1,020 

1,100 

1,180 

1,260 

1,340 

1,420 

1,510 

1,600 


Spillway      Apron  fill, 
fill,  cub.  yds.  cub.  yds. 


26 

32 

42 

55 

70 

90 

115 

145 

180 

220 

260 

300 

340 

360 

400 

450 


5 

5.5 

6 

6.5 

7 

8 

9 
10 
11 
12 
13 
14 
15.5 
17 
18.5 
20 


STRUCTURAL   TYPES  209 

Sluices  of  any  type  may  be  arranged  in  a  timber  spillway.  To  decide 
between  timber  and  concrete  spillways  is  practically  wholly  a  question 
of  comparative  cost  and  of  the  maintenance  and  repair  charges. 

Diagram  30  gives  the  approximate  first  cost  of  the  timber  spillway 
superstructure  of  the  types  here  described,  per  linear  foot  of  the  spill- 
way, and  comparatively  with  the  cost  of  concrete  spillways  for  different 
heights  and  varying  market  values  of  timber  and  of  concrete,  both 
placed  in  the  structure. 

Fig.  57,  section  II,  shows  a  modification  of  the  timber  spillway, 
the  upstream  side  being  inclined  on  half  horizontal  in  one  vertical  and 
the  apron  fully  sheeted  to  the  shape  of  the  overfall  curve;  its  charac- 
teristics are:  S  =  16  ft.,  B  =  1.75  S,  C  =  0.357  B. 

ARTICLE  71. — Occasionally  it  may  be  desired  to  construct  the  spill- 
way at  first  to  only  a  part  of  the  total  height  to  be  ultimately  utilized; 
this  is  practicable  both  with  the  solid  and  the  gravity  types.  For  the 
first  the  downstream  slope  should  then  be  left  in  steps  with  dowels,  in 
order  to  secure  the  best  practicable  connection  for  the  future  addition 
to  the  original  section;  the  foundation  and  the  apron  must  be  sufficient 
for  the  final  height.  For  gravity  spillways  the  partitions  are  likewise 
stepped  on  the  apron  side  and  are  covered  with  a  timber  instead  of  the 
concrete-steel  apron,  the  latter  being  constructed  when  the  spillway  is 
completed  to  its  final  height. 

Or  it  may  be  desired  to  raise  an  existing  spillway,  which  may  also 
be  practicable  but  cannot  .be  treated  in  a  general  manner;  each  such 
case  must  be  considered  from  its  own  conditions. 

ARTICLE  72.  Spillway  Abutments. — The  spillway  terminates  in  abut- 
ments which  may  be  of  natural  rock  walls  when  the  location  is  in  a 
palisaded  gorge;  but  in  the  majority  of  cases  the  spillway  does  not 
complete  the  empounding  of  the  watercourse,  and  the  additional  struc- 
tures, which  are  required  to  dam  the  river,  are  joined  on  the  spillway, 
and  the  abutments  then  form  the  connecting  links. 

Abutments  should  be  of  the  same  height  as  the  adjoining  reservoir 
structures,  not  less  than  three  feet  above  the  maximum  overflow  level, 
and  in  outline  they  must  be  of  sufficient  dimensions  to  cover  completely 
the  ends  of  the  banks  which  they  are  to  protect  against  the  overflowing 
water;  they  have,  however,  little  in  common  with  bridge  abutments, 
partaking  rather  of  the  character  of  retaining  walls.  For  solid  spillways 
the  section  proper  needs  no  abutment,  which  is  formed  around  and 

14 


210 


HYDRO-ELECTRIC   PRACTICE 


overlapping  it  on  all  sides  as  much  as  the  section  of  the  adjoining  reservoir 
structures  require;  for  gravity  spillways  the  abutment  becomes  a  com- 
plete wall,  forming,  in  part,  the  end  partition  of  the  spillway;  while 
for  timber  spillways  the  abutment  is  a  separate  structure  throughout. 

The  abutments  may  be  of 
timber,  masonry,  concrete,  or  of 
concrete -steel  construction, 
their  design  being  based  upon 
the  theory  of  earth-retaining 
structures. 


Fig.  58,  B  E  K,  is  an  earth 
bank,  <p  its  angle  of  repose,  B  E 
the  slope  of  rest ;  a  wall,  D  E  F  J, 
is  erected  and  the  space  between 
it  and  the  bank  B  D  E  is  filled 
with  similar  material  as  is  in 
the  bank.  It  is  assumed  that  if  the  wall  is  suddenly  removed  a  portion 
of  the  fill,  represented  by  C  D  E,  would  follow  after  it,  and  the  slope  of 
rupture,  C  E,  is  accepted  as  being  the  bisect  of  an  angle  =  90°  -  <p. 

This  theory  is  not  well  proved, — that  is,  as  to  the  locus  and  form 


D 


BD 


C 


Fig.  59     „ 
B 


/ 


w  H.E.R116 

H.v.S. 


of  the  line  of  rupture;  it  may  be  accepted  as  representing  the  conditions 
of  a  sand  bank,  provided  it  is  dry. 

The  author  has  examined  a  number  of  slides  in  canal  banks  of  from 
20  to  40  feet  high,  chiefly  of  clay,  gravel,  and  sand  formation,  with  a 
view  of  determining  the  causes  and  effects  of  such  subsidences,  and  has 
found  the  lines  of  rupture  to  be  always  vertical  for  one-third  to  one-half 


c 

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Diagram  30 
Comparative  cost  of 
Timber  &  Concrete 
Spillways 

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211 


212 


HYDRO-ELECTRIC   PRACTICE 


of  the  height,  then  sloping  along  the  plane  of  rest,  approximately  as  shown 
in  Fig.  59,  section  I,  for  clay,  gravel,  and  sand,  section  II,  for  clay  and 
gravel,  and  section  III,  for  clay.  The  slopes  of  these  three,  when  contain- 
ing only  normal  quantities  of  water,  were  found  to  be  practically  the 
same,  being  from  1.5  to  2.5  horizontal  to  one  vertical;  the  locations  and 
lines  of  rupture  were  likewise  similar  in  each  case,  the  surface  break  C 
being  generally  midway  of  DB,  the  top  of  the  slide  vertical  and  then 
generally  curving  to  the  toe  of  the  slide  at  E,  and  the  vertical  sections 
increased  in  length  as  the  ratio  of  sand  and  gravel  decreased. 


The  forces  to  be  resisted  by  the  retaining  structure  originate  in  the 
wedge-shaped  portion  of  Fig.  60,  CDE,  which  would  fall  if  the  wall  were 
removed;  the  area  of  this  part  A'  is  some  fraction  of  the  rectangle  hd, 
which  will  here  be  assumed  in  accordance  with  the  observations  above 
detailed  to  have  the  following  values  for  different  materials: 

for  sand  or  half  gravel  and  sand  or  loam  A'  •=  0.5  hd, 

for  clay,  gravel,  and  sand A'  =  0.6  hd, 

for  clay  and  gravel  A'  =  0.7  hd, 

for  clay A'  =  0.8  hd, 

provided  that  the  subdrainage  of  the  fill  is  sufficient  to  prevent  any 
accumulation  of  water  in  the  bank  or  against  the  wall. 

h  =  height  of  retaining  wall,  and  d  =  h  tan — ®  =  h  tan  a ; 

Zi 

A'  =  rh2  tan  a,  in  which  r  is  the  ratio  of  the  area  hd  of  the  falling  part 
as  per  class  of  material; 


STRUCTURAL   TYPES 


213 


W'  =  w'rh2  tan  a,  in  which  w'  is  the  weight  in  Ibs.  per  cubic  foot  of  the 

material  of  which  the  fill  consists; 
W  is  assumed  to  act  in  the  gravity  line  Gg  of  Fig.  61,  on  the  line  of 

rupture  CE; 
GR  represents  the  reaction  of  the  bank  and, 


P  =  W  X  r  the  reaction  of  the  wall 


^  H.E.P.120 
y<*       H.V.S. 


=  W'rhd  X  r  =  wrd2  =  wrn2  tan2  a 
n 


its  horizontal  component 


HP  =  P  cos  $  =  w'rh2  tan2  a  cos  <£,  which  is  the  force  to  be  resisted  by 
the  wall  and  is  assumed  to  be  concentrated  at  a  point  0,  being  -  above 

o 

the  base  EF. 

The  moment  of  pressure  is  the  product  of  P  into  the  lever  arm  I/  =  - 

o 

MP  =  ^-3  tan2  a  cos  <p. 
<j 

Diagrams  31,  32,  and  33  give  values  of  MP  for  different  heights 
and  classes  of  material;  the  weight  w'  and  the  angle  of  repose  <£  are 
those  given  in  Article  52. 


214  HYDRO-ELECTRIC   PRACTICE 

The  wall  should  be  designed  for  a  safety  factor  of  "2"  or  MW  = 
2  MP.  Ex.  1  of  a  timber  retaining  crib  20  feet  high,  the  fill  being  of 
gravel  and  sand; 

<£  =  28°,  a  =  31°,  tan  a  =  0.60,  cos  $      =  0.883,  r     =  0.5, 

h  =  20,  w'  =  94; 

A'  =  rh2     tan  a  =        0.5  X  203  X  0.60  =  120  sq.  ft.; 

W  =  wrh2  tan  a  =       120  X  94  -  11,280  Ibs.; 

P  =  wrh2  tan2  a  =  11,280  X  0.6  =    6,768  Ibs.; 

HP  =  wrh2  tan2  a  cos  $  =  6768  X  0.883     =    5,976  Ibs. ; 

MP  =  ™^L  tan2  a  cos  $  =  5976  X  6.66      =  39,800  ft.  Ibs. 
o 

Fig.  62,  section  I,  is  a  crib  20  feet  high  and  12  feet  wide  filled  with 
gravel  and  sand. 

A  =  240  sq.  ft.,  A  fill  =  0.75  A  =  180  sq.  ft., 

w  =    94  Ibs.,  L        =  6  ft., 

.    W  =  180  X  94  -    16,920  Ibs., 

MW  =  WL  =  16,920  X  6          =  101,520  ft.  Ibs., 
SSF  =    16,920  *  11,280  =  1.5, 

PSF  =  101,520  -*-  49,800  =  2.04. 

Fig.  62,  section  II,  represents  the  practical  design  of  such  a  timber 
crib  abutment  with  its  bank  side  stepped. 

Fig.  63,  section  I,  is  of  a  gravity  retaining  wall  of  cyclopean  or  mono- 
lithic concrete  20  feet  high  and  8  feet  wide. 

A  =  160  sq.  ft.,  w  =  140  Ibs.,  L  =  4  ft., 

W  -  22,400  Ibs.,       MW  =  89,600  Ibs., 
SSF  =  2  PSF  =  2.25. 

Fig.  63,  section  II,  shows  the  practical  design  with  a  battered  face 
and  footing. 

Diagram  32  gives  quantities  of  material  required  for  gravity-con- 
crete retaining  walls  of  different  heights. 

Concrete-steel  retaining  walls  consist  of  a  vertical  concrete-steel 
curtain  wall  divided  into  spans  of  equal  lengths  by  concrete-steel  counter- 


15 
14 
13 
12 
11 
10 


Diagram  31 
Retaining  Wall 

Pressure  Moment 
HP=[MP-=-  h]x3 


-a- 


± 


&    .£ 
f/      (57 


5 


Z 


Z 


O  *4 


215 


160 

/ 

150 

Diagram  32 
Retaining  Wall 

Pressure  Moment 

HP=[MP-*-h]x3 

/ 

140 

/ 

/ 

/ 

/ 

130 

y 

/ 

/ 

120 
110 

/ 

/ 

/ 

/ 

/ 

7 

i 

/ 

/ 

100 
90 
80 
70 
60 
50 
40 
30 
20 
10 

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216 


450 
420 
390 
360 
330 
300 
270 
240 
210 
180 
150 
120 
90 
60 
30 
°c 

/ 

/ 

/ 

/ 

Diagram  33 

/ 

/ 

/ 

/ 

/ 

Retaining  Wall 

/ 

y 

/ 

/ 

/ 

/ 

Pressure  Moment 

/ 

/ 

3 

f 

/ 

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HP=[MP-*-h]x 

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O             ON             O             -H             r*              fi'ttnvAOODONC 

217 


218 


HYDRO-ELECTRIC    PRACTICE 


forts.  The  overturning  forces  are  transmitted  to  and  resisted  by  the 
counterforts,  the  curtain  wall  between  them  being  designed  as  beams 
fixed  at  both  ends  and  uniformly  loaded. 

Fig.  64,  sections  I  and  II,  HP  as  before  =  wh2  tan2  a  cos  <p;    the 
thrust  at  the  counterforts  is 

HPsp  =  wh2  tan2  a  cos  <p  X  span,  and  the  bending  moment  at  FE 


Mo  = 


w'rh3 


tan2  a  cos  <p  X  span  ft.  Ibs. 


Figf.  63 

Gravity 
Retaining  Wall 


H.E.P.121 
H.v.S. 


Mo4  in  inch  pounds,  in  which  4  is  the  assumed  safety  factor,  is  the  force 
which  must  be  safely  resisted  by  the  section  at  the  base  of  the  counter- 
fort the  top  of  which,  at  the  crest  of  the  retaining  structure,  may  be 
the  practicable  minimum.  The  force  against  the  wall  between  counter- 
forts is  assumed  to  be  the  uniform  pressure  of  HP  =  w'h2  tan2  a  cos  $ 

acting  at  a  point  which  is  -  above  the  base. 

o 

Fig.  64,  section  III,  ABC  represents  the  pressure  area  acting  against 
the  wall  BC. 

A'  =         =  HP;    considering  the  wall  to  consist  of  x  horizontal 
beams  each  one  foot  high  and  of  the  length  of  the  span,  and  denoting 


STRUCTURAL   TYPES 


219 


the  vertical  distance  of  the  centre  of  the  beam  to  the  top  of  the  wall 
by  n  feet,  then  is  the  load  per  linear  foot  of  beam 

2TTP 

W  at  B  =  -      -  and  for  any  successive  beam  x  from  equation 


h  :  n  =  b  :  x,  and  x  = 


2HPn 


The  bending  moment  against  a  beam  fixed  at  both  ends  and  uniformly 


2  2 

loaded  is  Mo  =  ^  X  ^  =  ~^-'t  with  a  safety  factor  of  4  Mo  4  = 
TTT>I'>  1.2  n       LZ        /z  n 

—  to  which  the  concrete-steel  wall  at  the  bottom  must  be  adapted. 
18  h 


B 


G    / 


EJ'  X'l 

7.     ' 


-    Sp-- 


ii 


Fig.  64 

Concrete  Steel 
Retaining  Wall 
Cf 

III 


Rear  Elevation 


Section 


H.E.P.122 
H.v.S. 


Fig.  65  shows  the  section  and  elevation  of  a  concrete-steel  retaining 
wall.  Counterforts  are  spaced  10  feet  and  are  constructed  of  x  concrete; 
curtain  walls  are  of  xx  concrete. 


h  =  20  feet, 


=  28°,         r  =  0.5. 


Counterforts 


HP  =  5976  Ibs., 
MP  =  39,800  ft.  Ibs. 
for  a  span  of  10  feet     MP  =  398,000  ft.  Ibs. 

Mo  4  =  19,104,000  inch  Ibs., 


for  a  section  12  inches  wide  the  depth  at  the  bottom  of  the  counterfort 


220  HYDRO-ELECTRIC   PRACTICE 

section  "  t "  is,  from  Art.  53, 

3620  t2  =  19,104,000, 
19,104,000       70  A  - 
1  =        3620       =  72'6  mcheS' 
and  the  steel  area  q  =  0.077  t  =  5.6  sq.  inches; 

the  practical  section  is  12  inches  wide  and  6  feet  deep. 


Fig.  65 


F^^%sgsx%ss£&a 
Section 


^'KConcrete  Steel 
Retaining  Wall 


H.E.P.123 


Curtain  wall,    the  bottom  beam  from 


Mo4  = 


"2 ^040 


the  actual  length  between  counterforts  is  only  9  feet,  but  it  is  taken  at 
the  full  span;  thickness  t  is  from 


5505  tj  =  239,040,  t  =  =  6.6  inches; 

X     5505 


STRUCTURAL  TYPES  221 

the  minimum  practical  section  of  the  wall  will  be  12  inches  at  the  bottom 
and  8  inches  at  the  top  with  the  proper  section  of  reinforcing  steel. 

Returning  to  the  consideration  of  the  spillway  abutment,  it  has 
already  been  noted  that  it  is  a  retaining  wall  only  in  part, — that  is,  the 
portion  covering  the  spillway  end  is  not  chargeable  with  resistance  to 
bank  pressures  which  at  that  point  are  transmitted  to  the  spillway 
proper ;  only  the  top  and  the  downstream  portion  of  the  abutment,  which 
overlap  the  spillway,  partake  of  the  duties  of  retaining  walls  and  should 
be  designed  in  accordance  with  the  theory  herein  developed  and  as 
shown  on  Fig.  65  in  plan,  elevation,  and  section. 

Approximate  quantities  of  material  required  for  concrete-steel  abut- 
ments of  various  heights  have  been  given  in  Part  I,  Diag.  12,  Article  23. 

The  selection  of  the  spillway  abutment  type  is  practically  entirely 
determined  by  a  consideration  of  cost ;  the  crib  abutment,  like  the  timber 
spillway,  will  in  time  call  for  repairs,  however,  of  no  such  cost  and  fre- 
quency as  in  the  case  of  the  spillway;  the  gravity  and  concrete-steel 
structures  are  both  of  like  permanent  character. 

In  many  cases  waste-flumes,  as  will  be  noted  later  on,  are  most 
economically  arranged  through  the  abutments,  in  which  event  the  con- 
crete-steel type  has  the  decided  advantage  on  account  of  its  small  trans- 
verse section  as  compared  with  the  others;  this  is  also  true  when  the 
water  is  to  be  diverted  from  the  upper  pool  by  means  of  a  pressure  line, 
the  intake  to  which  is  frequently  most  conveniently  and  economically 
arranged  through  the  abutment. 

ARTICLE  73.  Reservoir  Dams. — When  the  spillway  completes  the 
closing  of  the  river  valley  and  the  empounding  of  the  upper  pool, — i.e., 
in  case  the  river  flows  between  natural  rock  banks,  which  rise  above  the 
greatest  flood  level, — no  other  control  works  are  required  in  connection 
with  the  dam;  but  where  this  is  not  the  case,  as  in  the  event  of  the  spill- 
way taking  up  only  a  portion  of  the  river  valley,  generally  the  natural 
width  of  the  stream,  and  the  main  valley  banks  are  at  a  distance  from  the 
river  proper,  the  reach  from  the  spillway  to  these  banks,  where  they  rise 
to  the  required  height  above  the  greatest  overflow,  must  be  closed  by 
additional  structures,  which  really  form  the  dam,  serving  the  purpose  of 
empounding  only, — that  is,  no  flow  is  to  pass  over  it  at  any  time.  These 
structures  may  be  of  a  variety  of  types,  generally  classified  as  reservoir 
embankments  and  bulkheads,  the  first  consisting  of  rock  or  earth  or  both, 
the  latter  of  masonry,  concrete,  or  concrete-steel. 


_.  HYDRO-ELECTRIC    PRACTICE 

* 

Earth  and  rock-fill  dams  have  been  constructed  for  centuries  to  the 
greatest  heights.  Their  design  must  be  such  that  the  weight  represented 
by  their  section  safely  resists  the  hydrostatic  pressure  of  the  water  which 
stands  against  them,  that  no  water  passes  under  or  through  them,  and 
that  their  exposed  slopes  are  safeguarded  against  erosion  due  to  rainfall. 
The  stability  theories  heretofore  developed  in  connection  with  spillways 
and  retaining  walls  also  apply  in  this  case,  and,  as  the  pressed  surface  of 
these  structures  is  always  inclined  from  the  vertical,  the  pressure  theories 
involved  are  specifically  similar  to  those  discussed  in  behalf  of  gravity 
spillways,  with  this  exception,  however,  that,  instead  of  H  exceeding  the 
height  of  the  structure,  as  in  the  spillway,  it  is  always  less  than  the  height 
of  the  dam,  the  highest  water  level  should  not  rise  nearer  than  3  feet  to 
the  dam  crest.  Assuming  the  limits  of  spillway  overflow  as  before  at 
0.2  of  their  heights,  and  providing  this  minimum  clearance  of  3  feet, 
the  height  of  reservoir  structures  H'  will  be  at  an  elevation,  referred  to  the 
footing  level  of  the  spillway,  of  H'  =  1.2  S  +  3,  while  their  actual  height 
will  depend  upon  the  elevation  of  the  location  they  occupy. 

Preventing  water  from  passing  under  or  through  a  rock  or  earth-fill 
dam  can  be  accomplished  successfully  only  by  an  efficient  cut-off  below 
its  foundation  and  a  core  of  some  impermeable  material  in  its  body.  The 
subject  of  cut-off  is  to  be  treated  identically  as  heretofore  discussed  in 
connection  with  the  spillway  foundation,  and  everything  that  has  been 
there  presented  applies  here;  and  the  core  is  the  upward  continuation  of 
the  cut-off,  and  like  it  may  be  of  various  types, — namely,  a  timber  or 
steel  curtain,  clay  or  concrete  wall,  the  choice  depending  upon  the  height 
of  the  structure,  availability  of  material  and  its  comparative  cost.  The 
core  is  joined  to  the  abutment  and  a  drain-pipe  is  placed  at  its  base  on 
the  upstream  side,  passing  through  the  abutment  and  discharging  below 
the  spillway. 

Fig.  66  shows  the  section  of  an  earth  and  rock-fill  reservoir  embank- 
ment, being  chiefly  conditioned  with  a  view  to  the  preservation  of  its 
slopes,  and  when  this  is  fulfilled  its  area  and  the  corresponding  weight 
are  largely  in  excess  of  those  required  for  its  stability  against  the  active 
pressures.  The  upstream  slope  is  constantly  exposed  to  the  water,  which 
may  penetrate  into  the  material  and  have  a  tendency  to  wear  away  the 
surface,  which  can  be  counteracted  only  by  giving  it  an  inclination  of 
not  less  than  two  and  one-half  horizontal  in  one  vertical,  and  provided 
the  material  of  which  it  is  formed  is  of  the  proper  kind  and  is  placed  in 


STRUCTURAL   TYPES 


223 


the  manner  which  will  be  further  on  described.  At  the  water  surface 
especially  will  the  wave  action,  ice,  and  impact  of  floatage  make  inroads 
into  the  unprotected  bank,  and  the  upper  portion  of  this  slope,  for  a 
depth,  covering  the  entire  range  of  surface  fluctuations,  must  be  covered 
by  a  pavement  properly  laid,  and  in  fact  it  is  good  practice  to  extend  this 
pavement  to  one-third  the  water's  depth.  When  the  best  material  for 
earth  dams  cannot  be  obtained,  it  may  be  advisable  and  prove  economical 


Fig.  66 

Reservoir 
Embankment 


H.E.P.127 
H.V.S. 


to  flatten  the  upstream  slope  and  cover  it  entirely  with  a  blanket  of 
concrete  of  a  lean  mix,  which  may  be  maintained  in  position  by  driving 
iron  rods  one  inch  in  diameter  and  eight  feet  long,  spaced  8  ft.  c.  to  c., 
into  the  bank,  their  upset  ends  being  imbedded  in  the  concrete  sheet; 
such  rods  are  most  conveniently  driven  by  means  of  a  pipe  hammer, 
a  five-feet  long  piece  of  inch-and-a-half  iron  pipe  closed  at  one  end,  which 
is  slipped  over  the  rod  and  used  as  a  driver,  being  exchanged  for  a  shorter 
piece  as  the  rod  goes  down.  As  the  downstream  slope  is  exposed  to  the 
rainfall,  its  inclination  should  be  at  least  one  and  one-half  horizontal  in 
one  vertical  and  it  should  be  covered  with  grass  turf;  the  Bermuda  variety 


224  HYDRO-ELECTRIC    PRACTICE 

is  especially  valuable  on  account  of  its  long  roots  and  thick  growth. 
When  the  slope  exceeds  30  feet  in  length,  it  should  be  broken  midway 
by  a  horizontal  berme,  not  less  than  five  feet  wide,  to  check  the  down- 
flow  of  the  run-off  and  thereby  break  its  force.  The  crest  should  be  of  a 
least  width  equal  to  half  the  height  and  slightly  rounded  upward  in  the 
centre  to  prevent  the  collection  of  pools  of  water;  it  should  preferably 
not  be  used  as  a  highway,  but,  if  serving  this  purpose,  it  should  be  covered 
with  road-metal.  It  is  a  good  practice  to  plant  trees  along  the  crest,  as 
their  roots  will  strengthen  the  bank;  they  should,  however,  not  be  set 
closer  than  five  feet  to  the  break  of  the  crest  into  slope,  nor  should  they 
be  of  rapid  growth  or  of  widely  branching  type  which  present  large  sur- 
faces to  the  wind. 

The  selection  of  the  material  for  reservoir  embankments  deserves  the 
most  careful  consideration.  There  is  a  great  difference  between  the 
requirements  of  a  railroad  embankment  and  one  to  maintain  a  reservoir; 
in  the  former  proper  drainage  and  the  confining  of  the  slope  toes  will 
generally  be  a  sufficient  guarantee  for  its  permanency,  and  apparent 
weak  places  are  readily  accessible  and  can  be  strengthened  in  time; 
not  so  with  the  reservoir  structure,  one  side  of  which  is  constantly  sub- 
merged, where  leaks  are  not  easily  traceable  and  are  more  difficult  of 
access.  The  desideratum  is  an  impervious,  homogeneous  mass,  which 
may  be  classed  as  puddle,  consisting  of  such  proportions  of  gravel,  sand, 
and  clay  that  the  voids  in  the  mass  are  practically  filled.  Gravel,  from 
the  largest  size  passing  a  six-inch  ring  down  to  coarse  sand  grains,  packs 
with  34  per  cent,  of  its  volume  in  voids,  and  if  deposited  in  shallow 
layers,  not  exceeding  six  inches  in  depth,  and  covered  with  a  'two-inch 
layer  of  fine  sand,  the  latter  can  be  completely  washed  into  the  gravel 
strata,  as  can  a  succeeding  layer  of  one  inch  of  clay  or  preferably  loam. 
This  represents  an  expensive  programme  and  will  rarely  be  adopted,  but 
is  outlined  here  as  yielding  the  ideal  conglomerate  for  reservoir  banks. 
In  practice  gravel,  sand,  and  loam  are  spread  jointly  in  6  to  8  inch  deep 
layers  by  means  of  horse-scrapers,  well  watered  from  sprinkling  carts,  and 
compacted  with  heavy  iron  rollers ;  all  operations  and  handling  of  materials 
should  be  so  arranged  as  to  co-operate  in  the  most  thorough  compacting  of 
the  mass.  This  treatment  would  be  incomplete  without  recording  a  most 
emphatic  warning -against  the  dumping  of  material  from  cable-way  or 
derrick  buckets  or  from  tram-cars  operating  on  a  trestle,  as  material  so 
deposited  does  not  compact  nor  mix  as  required  for  reservoir  embankments. 


Fig.  67 
Reservoir  Bulkhead 


15 


H.E.P.1I8 
H.V.S. 

225 


226  HYDRO-ELECTRIC   PRACTICE 

Clay  should  be  used  but  sparingly;  in  large  masses  it  represents  the 
most  unstable  and  treacherous  material,  and  should  be  shunned,  for  the 
purpose  of  reservoir  embankments,  as  quicksand  in  a  railroad  cut.  Clay 
expands  and  contracts,  in  ratio  of  its  degree  of  dampness,  to  such  an 
extent  that  no  bank  largely  formed  of  it,  no  matter  of  what  dimensions, 
represents  stability  or  permanency. 

Sand,  confined  in  place,  forms  an  excellent  bank  material,  and,  as 
before  stated,  when  combined  with  gravel  and  loam,  it  yields  the  best. 

An  earth  embankment  with  a  concrete  core  consists  of  two  parts, — 
the  upstream  and  the  downstream, — the  exposure  and  wear  of  which 
differ  greatly;  the  former  is  submerged  and  subjected  to  wave  action 
and  whatever  effect  floatage  and  ice  may  have  upon  it,  while  the  latter 
merely  adds  to  the  weight  of  the  whole  and  is  exposed  to  the  rainfall. 
It  appears,  therefore,  altogether  logical  that  the  two  parts  should  be 
differently  composed;  for  instance,  the  upstream  section  might  be  built 
of  the  before-described  puddle,  and  the  downstream  of  a  loose  rock-fill 
with  sand  and  loam  washed  into  the  voids  and  a  sufficient  thickness  of 
loam  slope  covering  on  the  top  of  it  to  give  sustenance  to  a  grass  turf. 
If  the  core-wall  is  of  sufficient  stability,  such  an  embankment  will  be 
fully  as  effective  as  if  it  were  formed  entirely  of  puddle  material,  while, 
with  rock  available  in  the  vicinity,  its  cost  will  be  considerably  less. 

The  hydraulic-fill  dam  is  a  specific  type  of  earth  dam,  because  of 
the  method  of  its  construction,  which  consists  in  washing  the  desired 
material  from  a  higher  bank,  conducting  it  in  flumes  passing  above  the 
dam  site,  and  depositing  it  in  a  semi-liquid  state.  By  this  process  a  very 
compact  and  thoroughly  mixed  mass  may  be  secured,  and  this  represents 
the  best  method,  provided  suitable  material  is  in  close  proximity  at 
such  elevations  that  it  can  be  sluiced  by  gravity  for  the  major  portion  of 
the  dam,  and  provided  that  the  cost  of  pumping  is  not  too  great.  Some 
high  structures  of  this  class  have  been  erected  on  the  Pacific  coast. 

Approximate  quantities  required  for  earth  embankments  of  various 
heights  are  given  in  Diagram  14,  Article  26. 

Concrete-steel  bulkheads  (Fig.  67)  are  available  for  reservoir  duty. 
They  consist  of  an  inclined  concrete-steel  shell  supported  by  buttresses 
of  like  construction,  their  designs  being  based  upon  the  same  theories 
heretofore  developed  in  connection  with  the  gravity  spillway,  with  this 
important  exception,  however,  that  no  water  is  to  pass  over  them,  as  they 
should  rise  to  the  same  height  as  that  given  for  reservoir  embankments. 


STRUCTURAL   TYPES 


227 


The  connection  of  such  bulkheads  with  the  spillway  is  by  means  of  con- 
crete-steel abutments,  and,  in  alluvial  locations,  they  are  founded  upon 
bearing  piles  and  concrete  base  with  a  cut-off  in  the  manner  described  for 
the  spillway.  Diagram  15,  Article  26,  gives  approximate  quantities  of 
materials  required  for  concrete-steel  bulk- 
heads of  various  heights. 

The  decision  as  to  the  type  of  reservoir 
structures  is,  like  that  of  abutments,  chiefly 
a  matter  of  cost  comparison. 

ARTICLE  74.  Appurtenances  of  Spill- 
ways and  Dams. — Provisions  must  be  made 
to  unwater  the  upper  pool  in  order  to  ex- 
amine and  repair  the  dam  works  on  that 
side  and  to  remove  accumulations  of  sedi- 
ment and  drift.  Underflow  sluices,  already 
described  in  connection  with  the  open  spill- 
way design  in  Article  68,  are  available  for  this  purpose,  and  can  be  arranged 
through  the  spillway,  the  abutments,  or  reservoir  dam,  being  formed  of 
wooden  stave  or  steel  plate  pipes  or  of  concrete-steel  culverts  or  conduits. 
The  theory  of  discharge  through  submerged  orifices  is  based  upon  the 

fundamental  law  of  flow  of  water,  expressed 
by  v  =  ^2gh,  v  being  the  velocity  per 
second,  in  feet,  with  which  a  body,  falling 
freely  in  a  vacuum,  passes  through  the 
height  h,  g  representing  the  acceleration 
of  gravity  in  feet  per  second  =  32.2  ft., 
which  of  course  changes  with  the  distance 
from  the  centre  of  gravity,  the  earth's 
centre,  the  above  value  being  sufficiently 
correct  for  these  requirements. 

In  Fig.  68  CB  is  a  partition  or  wall, 
nl  is  a  square,  rectangular,  or  circular 
opening,  S  is  the  surface  level  of  the  water;  then  SI  -  ml  =  Sm  is  the 
head  H  under  which  the  water  passes  through  the  opening.  The  theo- 
retical discharge  would  therefore  be  expressed  by  Q  =  area  of  opening 
in  square  feet  into  v  theoretical  velocity,  but  actually  both  of  these 
factors  are  reduced  from  their  theoretical  values  by  coefficients  of  area 
and  of  velocity. 


228  HYDRO-ELECTRIC    PRACTICE 

Fig.  69  illustrates  the  characteristics  of  the  actual  approach  of  the 
water  to  such  an  opening,  from  which  it  is  evident  that  a  considerable 
part  finds  its  way  to  the  opening  along  curved  paths,  by  which  some  of 
the  energy  which  moves  the  water  is  lost  in  friction,  and  the  theoretical 
velocity  due  to  H  is  not  fully  realized  when  the  water  reaches  the  opening ; 
this  reduction  is  expressed  by  a  coefficient  of  velocity  which  has  been 
fixed  from  the  results  of  many  observations,  for  the  practical  application 
to  this  purpose,  at  a  value  of  about  0.98. 

Fig.  70  shows  the  manner  in  which  the  water  enters  the  opening  and 
the  characteristics  of  its  flow  in  its  passage  through  the  orifice,  indicating 
the  close  adherence  of  the  films  of  water  to  the  full  perimeter  of  the 
opening  at  the  upstream  edge,  and  how,  by  continuing  for  a  time  their 
curved  approach  directions,  a  distinct  contraction  is  formed  in  the  body 
of  the  moving  water  at  CC',  followed  directly  by  its  gradual  expansion, 
and  by  experiments  carried  on  for  long  periods  it  has  been  found  that 

CC'  =  0.7854  nl,  and  mm'  =  0.5  nl. 

It  is  apparent  that  CC'  represents  the  smallest  efflux  section  and  in 
it  must  prevail  the  highest  velocity,  which,  however,  cannot  exceed  the 
velocity  of  origin,  namely  that  due  to  the  head  H.  The  greatest  volume 
of  discharge  is  therefore  represented  by  that  passing  through  the  section 
at  CC',  which  is  the  actual  volume,  to  wit: 

Q  =  area  at  section  C  C'  X  theoretical  velocity  X  0.98, 

CC'  :ln  =  0.7854  :  1  when 

In  =  1  X  1  then  CC'  =  0.78542  =  0.616,  or  when 

In  =  2  X  5  CC'  =  1.57  X  3.927  =  6.16,  or, 

if  the  entrance  be  of  circular  form,  the  area  being  =  0.7854  d2,  and  d  =  1, 

thenCC'  =  0.7854'  =  0.616; 

in  other  words,  0.61675  is  the  coefficient  of  contraction,  and  the  ratio  of  the 
actual  opening  area,  of  whatever  shape,  which  may  be  accepted  as  the 
efflux  area  and  as  the  actual  discharge  through  an  opening  in  a  thin 
vertical  wall  is 


Q  =  0.61  a  X  0.98  A/2gh  =  0.604aA/2gh  =  4.85aVh. 


STRUCTURAL   TYPES 


Fig.  70 


H.E.P.131 
H.V.S 


In  Fig.  71  the  same  principles  are  applied  to  an  underflow  sluice,  nl 
is  the  entrance  or  intake  through  which  the  water  enters  from  the  upper 
pool  and,  as  before,  contracts  at  CC' ;  by  this  contraction,  in  the  interior 
of  a  closed  conduit,  a  vacuum  is  formed  around  the  body  of  flowing  water, 
and  the  latter,  acting  under  the  influence  of 
the  original  energy,  expands  again,  and,  as 
appears  from  many  experiments,  its  velocity 
is  not  reduced  by  reason  of  its  flow  area  be- 
ing increased,  but  the  volume  of  efflux  at 
EE',  the  section  where  the  entire  area  of 
the  conduit  is  again  filled  with  water,  is 
greater  than  at  CC'.  This  increase  has  been 
determined  at  about  25  per  cent,  over  the 
efflux  from  a  thin-wall  opening,  by  which 
the  coefficient  of  discharge  from  an  under- 
flow sluice  becomes  0.61675  X  0.98  X  0.25 
=  0.7555,  and  therefore  Q  =  6  a  /\/H,  provided  the  free  efflux  is  at  or 
near  the  section  EE'  where  the  water  first  refills  the  conduit  section,  which 
point  is  about  2.75  nl  from  the  intake  section  nl. 

The  same  characteristics  prevail  if  the  conduit  protrudes  into  the 

upper  pool  for  a  similar  length  =  2.75  nl, 
but,  when  it  becomes  longer  than  this, 
energy  is  expended  in  overcoming  perime- 
ter roughness,  which  in  turn  diminishes 
the  velocity  and  therefore  reduces  the 
discharge;  this  enters  upon  the  theory  of 
"flow  through  pipes,"  which  is  treated  in 
like  detail  in  connection  with  the  discus- 
sion of  diversion  works.  Many  refinements 
may  be  added  to  above  outlined  theory 
when  the  application  is  for  the  purpose  of 
accurately  measuring  volumes  by  efflux 
from  orifices,  but,  for  the  designing  of  works  herein  considered,  no  com- 
mensurate advantages  can  be  secured  by  such  reasoning,  and  the  values 
are  sufficiently  correct  for  this  practical  use  when  expressed,  for  square  and 
rectangular  openings,  by  Q  =  6  a  \/H,  and  for  circular  openings,  by  Q  = 
4.75  d2  \/H,  where  H  is  always  the  head  above  the  centre  of  the  intake,  a  is 
area  of  the  intake  in  square  feet,  and  d  is  diameter  of  a  circular  intake. 


230  HYDRO-ELECTRIC    PRACTICE 

The  areas  of  the  underflow  sluices  required  to  draw  down  the  upper 
pool  in  a  given  time  can  be  determined  only  if  the  storage  volume  is 
known;  if  this  were  A  and  the  head  maintained  constant,  then  a  quantity 
equal  to  A  would  pass  through  the  sluice  in  A  -7-  6  a  V  H  seconds  of  time, 
and  with  a  constantly  dropping  head  the  time  t  =  2A  -f-  6  a  V  H ;  this, 
however,  represents  only  the  stored  volume,  to  which  must  be  added 
the  continuous  flow. 

Example. — Given  an  upper  pool  one  mile  long,  200  feet  wide,  and  30 
feet  deep  at  the  spillway,  representing  a  total  storage  volume  of  about  16 
million  cubic  feet,  to  which  is  to  be  added  the  continuous  low-flow  volume 
of  1000  cubic  second  feet,  and  the  pool  is  to  be  unwatered  in  6  hours; 
then  for  the  storage  volume  alone  from  t  =  2 A  -r-  6  a  V  H,  21,600  = 
32,000,000  -r-  30a,  H  being  taken  at  25  ft.,  a  =  32,000,000  -5-  648,000  = 
50  sq.  ft.,  to  which  must  be  added  sufficient  sluice  area  to  discharge 
the  continuous  flow  of  1000  sf.  flow  =  1000  X  21,600  =  21,600,000 
cubic  feet,  21,600  =  43,200,000  -H  30  a,  and  a  =  43,200,000  -*-  648,000  = 
67  sq.  ft.,  or  the  total  sluice  area  required  being  50  +  67  =  117  sq.  ft., 
which,  if  arranged  in  two  sluices,  would  call  for  an  area  in  each  of  60 
square  feet,  and  the  practical  dimensions  would  be  8  X  8,  or  if  circular, 
each  sluice  would  be  represented  by  an  88-inch  pipe. 

In  open  spillways  the  area  of  sluices  will  always  exceed  that  required 
for  unwatering  the  upper  pool,  as  they  are  proportioned  to  control  the 
flood  discharge  of  the  stream. 

The  construction  designs  of  sluices  have  been  treated  generally  in 
connection  with  open  spillways  in  Article  68,  and  so  have  the  different 
gate  devices. 

When  sluices  are  arranged  through  reservoir  dams  or  embankments, 
the  considerations  involved  do  not  differ  from  those  herein  discussed; 
the  structural  designs  must  provide  sufficient  safeguards  against  erosion 
of  any  portion  of  the  embankment  at  the  sluice  entrance  and  along  its 
location  through  the  body  of  the  fill. 

The  operation  of  the  gates  is  most  conveniently  arranged  by  a  well 
rising  upward  from  the  sluice  in  the  downstream  portion  of  the  embank- 
ment and  terminating  at  some  convenient  elevation  in  a  gate-house. 

When  log  chutes  are  required,  they  may  be  of  the  general  design  of 
overflow  sluices,  as  described  in  connection  with  the  open  spillway  in 
Article  68,  with  the  addition  of  floating  booms  to  intercept  and  guide  the 
logs  into  the  sluice,  a  sufficient  operating  platform  above  the  log  chute 


STRUCTURAL   TYPES  231 

from  which  the  logs  can  be  steered  through  the  sluice,  and,  if  the  sluice 
floor  is  more  than  5  feet  above  the  lower  pool  level,  of  a  log  apron  below 
the  sluice,  which  consists  of  an  incline  formed  of  timber  trestles  or  cribs 
along  which  the  logs  will  pass  into  the  lower  pool  without  being  damaged ; 
the  incline  should  not  be  steeper  than  3  horizontal  in  one  vertical  and  the 
depth  of  the  water  at  the  incline  toe  should  equal  half  the  vertical  height 
of  the  apron.  The  log  chute  is  best  placed  at  that  end  of  the  spillway 
where  the  abutment  can  be  utilized  to  give  support  to  the  log  apron, 
and,  if  its  operation  does  not  interfere  with  the  diversion  or  power  station 
programme,  the  power  end  of  the  spillway  is  the  preferable  one. 

In  many  States  the  law  requires  the  placing  of  fish-ladders  in  any 
structure  which  obstructs  the  normal  flow  of  streams,  in  order  to  enable 
the  migrating  species  to  reach  the  upper  parts  of  the  watercourse  during 
the  spawning  periods.  The  design  for  fish-ladders  may  be  selected  from 
a  variety  of  types,  generally  consisting  of  a  trough  leading  from  the 
spillway  crest,  at  a  shallow  overflow  sluice,  to  the  lower  pool.  The  inclina- 
tion of  the  fish-ladder  should  be  from  8  to  10  horizontal  in  one  vertical, 
its  width  not  less  than  6  feet,  and  the  depth  such  that  water  will  stand 
not  less  than  18  inches  deep  in  the  steps  of  the  ladder  as  shown  in  Fig.  72, 
where  the  arrows  indicate  the  leaping  or  swimming  passage  of  the  fish. 
The  structure  is  best  placed  at  a  spillway  end  where  it  may  find  support 
at  the  abutment,  which  latter  is  to  be  extended  sufficiently  downstream- 
ward;  the  ladder  proper  may  be  supported  on  timber  or  steel  trestles 
or  on  masonry  piers,  the  choice  depending  chiefly  upon  the  exposure  of 
the  ladder  to  the  overflowing  water.  In  open  spillways,  where  the  over- 
flow is  under  control,  fish-ladders  may  be  of  timber  construction,  with 
proper  consideration  for  winter  conditions;  in  connection  with  solid  spill- 
ways of  considerable  overflow,  fish-ladders  should  be  of  masonry  construc- 
tion. For  high  spillways  'the  ladders  are  best  arranged  in  several  flights. 

Ice-Fenders. — In  northern  latitudes  where  ice  forms  6  inches  and 
thicker,  the  resultant  thrust  against  the  spillway  can  be  greatly  dimin- 
ished by  securing  ice-fenders  to  the  upstream  face  of  the  solid  spillway; 
these  consist  of  two  or  more  12-inch  square  timbers  placed  as  stringers 
one  upon  another  with  staggered  joints  and  secured  to  the  spillway  by 
means  of  screwbolts  set  in  the  masonry;  the  top  stringer  is  flush  with 
the  spillway  crest,  with  an  up-slant  so  that  ice  will  rise  up  under  pressure. 

Flashboards  are  devices  by  which  the  upper  pool  level  is  temporarily 
raised  for  the  purpose  of  accumulating  an  increased  volume  of  water 


I 

E 


c- 


Timber  Fishladder 


Fig.  72 


u 


Longitudinal  Section 


,N 


Transverse 
Section 


Concrete  Fishladder 


Transverse 
Section 


H.E.P.133 
H.V.S. 


232 


) 


_  X5 v> ^  _ 

-3  —  ft -<3  - 


233 


234  HYDRO-ELECTRIC   PRACTICE 

during  a  non-operating  period.  In  this  manner  the  upper  pool  by  pondage 
is  utilized  as  a  storage  reservoir,  principally  during  the  low-flow  periods, 
by  placing  some  movable  addition  upon  the  spillway  crest,  arresting  and 
holding  the  natural  flow  in  the  upper  pool,  no  water  being  allowed  to 
overflow  the  spillway  or  pass  through  the  turbines  during  a  certain  period, 
generally  some  portion  of  the  night,  and  then  using  the  natural  flow 
plus  the  accumulated  volume  during  the  operating  period.  When  this 
proceeding  is  feasible, — which  is  not  always  nor  generally  the  case,  because 
it  interferes  with  and  disturbs  the  natural  conditions  of  the  flow  in  the 
stream  and  thereby  is  likely  to  interfere  with  the  rights  and  ownership, 
in  and  to  the  water,  of  others, — and  when  the  operating  period  can  be 
confined  to  ten  hours,  the  power  output  of  the  continuous  flow  can  in 
this  manner  be  practically  doubled. 

Many  different  devices  are  employed  for  flashboard  service,  mechani- 
cal, automatic,  and  hand  operated,  but  their  selection  should  be  guided 
by  the  conditions  under  which  they  are  to  be  used  as  relating  to  seasons, 
periods,  and  frequency  of  their  service.  When  they  are  to  be  employed 
during  the  winter,  in  northern  latitudes,  the  ice  conditions  must  be 
considered.  Fig.  73  shows  different  types  of  flashboards.  In  sections 
I  and  II  a  plank  flashboard  is  set  on  edge  upon  the  spillway  crest  resting 
against  strain  pins,  inclined  downstreamward  and  placed  into  holes  left 
in  the  spillway  masonry,  or  between  such  strain  pins,  the  latter  being 
arranged  in  a  double  row  and  staggered;  these  planks  may  be  so  placed 
by  being  handled  from  a  platform  above  or  from  flat-boats  held  in  place 
above  the  spillway  by  guide-lines  secured  to  shore  points  or  to  a  ferry 
line  crossing  the  stream  above  the  spillway.  This  type  of  flashboards 
answers  well  during  open  seasons  for  short  spillways;  the  strain  pins  are 
of  one-inch  wrought  iron;  it  is  advisable  not  to  fix  them  permanently 
into  the  masonry,  but  to  leave  holes  into  which  they  are  readily  set; 
the  planks  should  be  two  inches  thick  and  from  8  to  12  inches  wide, 
though  the  narrower  size  will  be  found  preferable  on  account  of  the 
greater  ease  of  handling  them;  and  the  planks  have  secured  to  them,  on 
their  sides,  iron  hooks  so  set  that  they  can  easily  be  grappled  into.  The 
planks  must  be  of  uniform  thickness  and  edged  so  that  they  will  match  up 
to  a  water-tight  wall  in  any  position.  It  requires  two  men  to  set  or  re- 
move these  flashboards;  they  are  inexpensive  and  can  be  quickly  handled. 

Sections  III  and  IV  show  a  shutter  flashboard  framed  of  two  or  three 
planks  in  lengths  from  6  to  10  feet  and  swung  from  rod  hinges  on  the 


STRUCTURAL   TYPES 


235 


upstream  side  of  the  spillway.  The  shutter  is  bound  by  iron  strapping 
and  has  secured  to  it  two  or  more  strut  rods  by  which  the  shutter  is 
supported  in  an  upright  or  inclined  position  when  erected,  these  rods 
falling  into  recesses  or  grooves  left  in  the  spillway  crest  for  that  purpose. 
They  are  operated  by  hand,  being  raised  to  the  surface,  strut  rods  thrown 
over  on  the  downstream  face,  and  the  shutter  then  raised  up  where  it 
will  be  held  by  the  water  pressure  of  the  rising  upper  pool ;  or  the  shutters 
may  be  arranged  to  rest  against  stationary  or  removable  strain  pins  as 
in  the  case  of  the  plank  flashboard. 


Fig.  74 


,     ~zri  .  ,  ii/Wif        j i   if  ii  './Jj'_ili|ir  'li     *    ii  I  -•"^jr      i     —  _ 


Air  vent 


Air  vent 


H.V.S. 


Wells  and  galleries  are  arranged  in  solid  spillways  for  the  purpose 
of  inspection,  means  of  communication  and  location  of  wire  cables; 
as  shown  in  Fig.  74.  Access  to  these  is  had  through  the  downstream 
side  of  the  abutments  and  a  casemate  entrance  arranged  in  the  down- 
stream slope  of  the  embankment.  They  are  formed  of  the  least  required 
dimensions;  air- vents  of  two-inch  galvanized  iron  pipe  are  placed  10 
feet  c.  to  c.  from  the  gallery  wall  to  the  spillway  apron  face,  with  a  slight 
downward  drop  to  prevent  water  from  passing  through  them. 

Bridges,  foot-ivalks,  and  operation  platforms,  for  one  purpose  or 
another,  of  timber  or  steel  construction,  may  be  arranged  on  the  spillway. 

ARTICLE  75. — Diversion  works  comprise  the  structures  conducting 
the  water  to  the  power  station ;  they  may  be  classified  as  canals,  flumes, 
and  pipe  lines. 


236 


HYDRO-ELECTRIC   PRACTICE 


Canals  serve  to  divert  volumes  exceeding  500  cubic  second  feet; 
their  design  is  based  upon  the  theory  of  flow  in  open  channels.  Fig.  75, 
section  I,  represents  an  open  channel  section  the  bed  of  which,  AB,  is 
in  a  horizontal  plane,  and,  if  this  condition  prevails  from  the  source  to 


Fig.  75 


II 


H.E.P.136 
H.V.S. 


the  terminal,  the  water  does  not  flow;  in  section  II  the  bed  AB  is  down- 
wardly inclined  and  the  water  flows  through  it,  its  surface  assuming  a 
slope  similar  to  that  of  the  channel  bed;  the  vertical  difference  of  the 
horizontal  plane  of  the  water  surface  at  A  and  B,  or  at  any  two  points, 


Fig.  76 


H.V.S. 


is  the  head  h  between  such  points,  which  causes  the  flow  and  which  is 
generally  expressed  in  terms  of  slope  S  =  h  -=-  d,  where  d  is  the  length 
of  the  channel  AB  and  both  are  in  like  units,  also  called  the  hydraulic 
gradient. 

Fig.  76,  section  I,  represents  the  natural  section  of  a  stream,  section 
II  that  of  a  constructed  channel;  ABCD  is  the  wet  perimeter,  "P";  the 
cross  sectional  area  A  of  the  stream,  divided  by  the  developed  length  of 


STRUCTURAL   TYPES  237 

the  wet  perimeter,  is  the  hydraulic  radius  "  R."  The  flow  in  open  channels 
depends  upon  the  values  of  S,  A,  P  and  the  degree  of  roughness  "n" 
of  P,  and,  from  the  relations  of  these,  expressions  have  been  developed, 
as  the  results  of  many  observations  and  experiments,  for  the  mean 
velocity  of  the  flow,  the  basic  form  of  which  is  : 

velocity  =  coefficient  into  the  square  root  of  R  X  S, 

v  =  C  V  R  S, 

in  which  C  is  the  variable  quantity  which,  according  to  the  present 
acceptation  as  deduced  by  Ganguillet  and  Kutter  from  results  found  by 
M.  Bazin,  is  expressed  as 


C  =  y  -j-  [1  +  (x  -r- 
y  =  a  +  (1  •*•  n)  +  (m  -H  s),  and  x  =  [a  +  (m  -~  s)]  X  n,  in  which 

1   is  a  constant  =  1.811  ft., 
a  is  a  constant  =  41.6, 
m  is  a  constant  =  0.00281,  and 
n  is  variable  ; 

its  values  for  the  application  to  diversion  canals  are  for 

channels  lined  with  dressed  planks  or  smooth  concrete  =  0.010 
channels  lined  with  rough  planks  or  rough  concrete  =  0.012 
channels  lined  with  smooth  natural  rock  =  0.017 

channels  lined  with  hard  gravel,  clay,  and  sand  =  0.025 

channels  lined  with  soft  alluvial  materials  =  0.03 

Ex.—  A  =  1000  sq.  ft.,  P  =  128  ft.,  R  =  7.8, 
S  =  0.0005,  n  =  0.025 

y  =  41.6  +  (1.811  -T-  0.025)  +  (0.00281  *  0.0005)  =  119.64 

x  =  [41.6  +(0.00281  -*•  0.0005)]  X  0.0005  1.18 

x  -r-  VR  =      0.42 

C  =  119.64  -r-  1.42  =    84.3 

V  =  84.3  ^  7.8  X  0.0005  =  5.26  sec.  ft. 

Values  for  the  factors  "y"  and  "x"  for  different  slopes  and  perimeter 
conditions  are  given  in  Tables  16  and  17. 


238 


HYDRO-ELECTRIC   PRACTICE 


TABLE  16.— y  =  a  +  (1 
S.  n  =  0.010 

.0001 250.8 

.0002 236.7 

.0003 232.0 

.0004 220.7 

.0005 228.3 

.0000 227.4 

.0007 226.7 

.0008 226.2 

.0009 225.8 

.001..  .    225.5 


n)  +  (m  H-  S). 

n  =  0.012 

n  =  0.017 

220.7 

175.7 

206.6 

161.6 

201.9 

156.9 

199.6 

154.6 

198.2 

153.2 

197.3 

152.3 

196.6 

151.6 

196.1 

151.1 

195.7 

150.7 

195.4 

150.4 

TABLE  17.— x  =  [a  +  (m  H-  S)]  X  n. 


.0001. 
.0002. 
.0003. 
.0004. 
.0005. 
.0006. 
.0007. 
.0008. 
.0009. 
.001.. 


0.70 
0.56 
0.51 
0.48 
0.47 
0.46 
0.45 
0.45 
0.44 
0.44 


0.84 
0.67 
0.61 
0.58 
0.57 
0.55 
0.54 
0.54 
0.53 
0.53 


1.18 
0.95 
0.87 
0.83 
0.80 
0.79 
0.77 
0.77 
0.76 
0.75 


n  =  0.025 
142.1 
128.1 
123.4 
121.1 
119.6 
118.7 
118.0 
117.5 
117.2 
116.8 


1.74 
1.38 
1.27 
1.22 
1.18 
1.16 
1.14 
1.13 
1.12 
1.11 


Analyzing  the  flow  formula  and  the  influence  of  its  variable  factors 
upon  the  resultant  velocity  value,  in  its  special  application  to  the  design- 
ing of  diversion  channels,  the  range  of  the  coefficient  of  roughness  can 
be  limited  to  those  conditions  of  lined  channels  by  which  permanency 
of  prism  is  absolutely  guaranteed,  as  only  in  extremely  rare  cases  would 
a  power  canal  present  any  other  conditions;  that  means  that  the  first 
three  values  of  "n"  fully  cover  the  various  perimeters  to  be  met  with  in 
this  subject,  and  that  the  value  of  "y"  is  between  150  and  250  and  of 
"x"  between  0.4  and  1.2,  and  within  this  scope  the  values  of  the  other 
pertinent  expressions  in  the  flow  formula,  such  as  x  -r-  V  R  and  of  "C, " 
are  given  in  the  following  tables. 

TABLE  18.— [1  +  (x  +  V  R)]. 

x  =0.5  x  =  0.6  x  =  0.7           x  =  0.8          x  =  0.9  x  =  1 

1.5  1.6  1.7  1.8  1.9  2 

1.35  1.42  1.50  1.57  1.64  1.70 

1.30  1.35  1.40  1.47  1.52  1.60 

1.25  1.30  1.35  1.40  1.45  1.50 

1.22  1.27  1.31  1.36  1.40  1.45 

1.20  1.25  .   1.29  1.32  1.37  1.40 

1.19  1.23  1.26  1.30  1.34  1.38 

1.18  1.21  1.24  1.28  1.32  1.35 

1.17  1.20  1.23  1.26  1.30  1.33 

1.16  1.19  1.22  1.25  1.28  1.32 


R 

x  =  0.4 

1  

1.4 

2  

1.28 

3  

1.23 

4  

1.20 

5  

1.18 

6  

1.16 

7  

1.15 

8  

1.14 

9  

1.13 

10  

1.12 

STRUCTURAL   TYPES  239 

This  completes  the  analysis  of  the  factor  "C"  in  the  flow  formula. 
Example.— n  =  0.012,  S  =  0.0003;  the  channel  is  to  divert  3000  cub. 
sec.  ft.  at  a  maximum  velocity  of  5  ft., 

A  =  600  square  feet, 

the  side  slopes  of    the  canal  are  to  be  1.5  horizontal  in  one  vertical, 
P  =  113  ft.  and  R  =  A  -r-  P,  =  600  -H  113  -  5.3, 
y  from  Table  16  =  201.90, 
x  from  Table  17  =  0.61, 

[1  +  (x  -r-  VR)]  Table  18  =  1.26,  and  therefore 
C  =  y  -5-  [1  +  (x  -5-  VR)]  =  201.9  -i-  1.26  =  160. 
Values  for  "C"  for  above  y,  x,  and  R  are  given  in  Table  19. 

TABLE  19.— C  =  y  -s-  [1  +  (x  -e-  v'R)]. 
y  1.1     1.2     1.3     1.4     1.5     1.6     1.7     1.8     1.9   2.0=[l  +  (x-s-v'R)] 


250  .  .. 

227 

208 

192 

179 

167 

156 

147 

139 

132 

125 

240  

218 

200 

184 

171 

160 

150 

141 

133 

126 

120 

230  

209 

191 

177 

164 

153 

144 

135 

128 

121 

115 

220  

200 

183 

170 

157 

147 

137 

130 

122 

116 

110 

210  

191 

175 

161 

150 

140 

131 

123 

117 

110 

105 

200  

182 

166 

154 

143 

133 

125 

117 

111 

105 

100 

190  

173 

158 

146 

136 

127 

119 

112 

105 

100 

95 

180 

164 

150 

138 

129 

120 

112 

106 

100 

95 

90 

170... 

.  154 

141 

131 

121 

113 

106 

100 

94 

90 

85 

160 145    133    123    114    107    100     94     90    84      80 

150 136    123    115    107    100     93     88    83     80      75 

Continuing  the  solution  of  the  previous  example,  "C"  can  be  taken 
off  Table  19  by  interpolation  and  the  velocity  found  from 


v  =  C  ^RS,  ^RS  =      5.3  X  0.0003  =  0.0398. 
v  =  160  X  0.0398  =  6.368. 

Velocity  in  a  diversion  canal  should  not  be  excessive;  as  a  rule,  it 
will  be  important  to  conserve  the  available  head  wherever  practicable, 
and  the  design  of  the  canal  affords  one  of  the  important  opportunities  to 


240 


HYDRO-ELECTRIC   PRACTICE 


practise  this  economy.  Only  where  the  excavation  of  the  canal  prism 
presents  a  very  costly  undertaking,  such  as  when  it  has  to  be  located 
through  a  hard  rock  ledge,  or  in  case  the  value  of  the  necessary  right  of 
way  is  practically  prohibitive  and  when  the  canal  section  therefore  must 
be  kept  at  a  minimum,  are  high  velocities  excusable ;  five  feet  per  second 
is  a  good  limit  to  be  adopted  for  the  flow  in  a  diversion  canal,  and  within 
this  limit  the  value  of  "v"  is  given  for  different  slopes  and  R  in  the  fol- 
lowing Tables  20  to  24. 


TABLE  20.— VELOCITY  FOR  S  =  0.0001. 


0.010 


0.012 


R 

C 

VRS 

v 

C               v 

1 

147 

0.01 

1.47 

120         1.20 

2              .    . 

168 

0.014 

2.35 

138        1.93 

3  

178 

0.017 

3.02 

149        2.53 

4 

186 

0.02 

3.92 

155        3.15 

5. 

191 

0.022 

4.20 

160        3.52 

6    . 

195 

0.024 

4.68 

164        3.93 

7  

198 

0.026 

5.34 

167        4.34 

8  

201 

0.028 

170        4.76 

9      

203 

0.03 

172        5.16 

10  

205 

0.03 

174        5,40 

TABLE 

21.—  VELOCITY 

FOR  S  =  0.0002. 

n  =  0.010 

0.012 

R 

C 

V'RS 

V 

C               v 

1          

151 

0.014 

2.11 

123         1.72 

2     

170 

0.02 

3.40 

140        2.80 

3 

179 

0.024 

4.29 

149        3.57 

4 

185 

0.028 

5.18 

155        4.34 

5  

190 

0.031 

5.89 

159        4.93 

6 

193 

0.034 

162        5.50 

7 

196 

0.037 

165        

8  

198 

0.040 

167 

9 

200 

0.043 

169        

10       

201 

0.045 

170        

TABLE 

22.—  VELOCITY 

FOR  S  =  0.0003. 

n  =  0.010 

0.012 

R 

C 

VRS 

V 

C               v 

1  

152 

0.017 

2.58 

124        2.10 

2  

171 

0.024 

4.10 

140        3.36 

3  

179 

0.030 

5.37 

152        4.56 

4  

185 

0.034 

156        5.30 

5  

189 

0.038 

.... 

159        

6  

192 

0.043 

162 

7  

195 

0.046 

164 

8  

197 

0.049 

166 

9  

198 

0.053 

168 

10  

200 

0.055 

169 

0.017 


C 

V 

81 

0.81 

96 

1.34 

104 

1.77 

111 

2.22 

116 

2.55 

119 

2.85 

122 

3.17 

124 

3.47 

126 

3.78 

128 

3.96 

0.017 

C 

V 

83 

1.16 

97 

1.94 

105 

2.52 

111 

3.11 

114 

3.53 

117 

3.98 

120 

4.44 

122 

4.88 

124 

5.33 

125 

5.62 

0.017 

C 

V 

84 

1.42 

97 

2.32 

105 

3.15 

111 

3.77 

114 

4.33 

117 

5.03 

119 

5.47 

121 

123 

.... 

124 

.... 

STRUCTURAL   TYPES 


241 


TABLE  23.— VELOCITY  FOR  S  =  0.0004. 

0.012 

C  v 

125  2.50 

141  3.94 

150  5.10 

157  6.28 

159  

161  

163  

165 
167 
168 


R 
1         

C 
154 

n  =  0.010 
V'RS 
0.020 

V 

3.08 

2              

171 

0.028 

4.78 

3      

180 

0.034 

6.12 

4 

184 

0.040 

5                .  .  . 

188 

0.045 

6 

191 

0.049 

7 

193 

0.053 

8 

195 

0.056 

9 

197 

0.060 

10.. 

.    199 

0.063 

0.017 


C 

85 
98 
105 
110 
113 
116 
118 
120 
122 
123 


1.70 
2.74 
3.57 
4.40 
5.08 
5.68 


TABLE  24.— VELOCITY  FOR  S  =  0.0005. 


R 
1. 
2. 
3. 

4. 
5. 
6.. 

7. 


9. 
10. 


C 

154 
175 
179 
184 
188 
191 
193 
196 
197 
199 


n  =  0.010 
V'RS 
0.024 
0.031 
0.039 
0.045 
0.050 
0.055 
0.059 
0.063 
0.067 
0.070 


3.68 
5.30 


0.012 


C 

125 
141 
150 
156 
158 
161 
163 
165 
167 
168 


3.00 
4.37 
5.85 


0.017 


C 
85 
98 
105 
110 
113 
116 
118 
120 
122 
123 


2.04 
3.04 
4.09 
4.95 
5.65 


By  aid  of  the  tabulated  values  in  these  nine  tables  all  problems 
relating  to  the  flow  in  a  diversion  canal  or  flume  can  be  solved  or  checked ; 
the  frequent  query,  of  what  the  slope  would  be  in  a  canal  of  certain 
prism  and  a  given  velocity  of  flow,  is  thus  solved. 

Example. — To  divert  800  cubic  second  feet  at  a  velocity  of  approxi- 
mately 5  feet  per  second  in  a  rectangular  sectioned  canal  5  feet  deep  and 
32  feet  wide;  what  will  be  the  slope? 

A  =  800  -v-  5  =  160  sq.  ft.,  R  =  160  -5-  42  =  3.8,  n  =  0.012, 

and  velocity  to  be  about  5  feet  per  second. 

From  Table  22  in  column  of  n  =  0.012,  and  between  values  for  R 
of  3  and  4,  the  desired  velocity  appears  and  the  slope  is  0.0003.  It  must 
be  noted  that  the  slope  is  expressed  in  the  ratio  per  foot  of  length,  a  slope 
of  0.0001  =  1.2  inch  per  1000  feet  and  6.33  inches  per  mile. 

Location,  construction,  and  operating  conditions  are  the  main  con- 
siderations for  the  designing  of  the  diversion  canal. 

16 


242  HYDRO-ELECTRIC   PRACTICE 

The  location  should  be  the  economically  shortest,  which  is  deter- 
mined by  the  cost  of  the  right  of  way  and  of  the  construction,  and  is 
most  readily  proved  by  the  method  of  elimination, — that  is,  by  making 
paper  locations  based  upon  the  survey  and  boring  data  and  rinding  the 
excavation  quantities  and  slope  areas  for  a  flow  section  of  one-fifth  of 
the  maximum  volume  to  be  diverted,  thus  assuming  a  trial  velocity  of 
five  feet.  Deviations  from  a  tangent  alignment  will  generally  prove 
justifiable  to  avoid  side-hill  cuts,  buildings,  road  crossings,  rock  outcrops, 
swamps,  and  to  secure  uniformity  of  the  prism,  but  curvature  should  be 
limited  to  3°. 

The  slope  in  curved  channels  is  greater  than  in  straight;  the  excess 
is  determined  from  Humphrey  and  Abbott's  formula, 

he  =  v2  X  6  d  -T-  536  p, 

where  v  is  the  mean  velocity,  d  the  total  angle  of  the  curve  expressed 
in  radians  (1°  =  0.01745),  and  p  =  3.1415. 

Example. — In  a  channel  with  v  =  5  ft.,  on  a  3°  curve  900  ft.  long,  the 
curve  slope  he  =  52  X  6  X  27  X  0.01745  -i-  1683, 

=  70.6725  -f-  1683  =  0.42, 

which  must  be  added  to  the  slope  in  a  straight  channel  of  the  same 
length,  or,  if  the  general  slope  in  this  case  is  0.00015,  the  total  slope  in 
this  curve  is  0.135  +  0.042  =  0.177  ft. 

The  construction  considerations  to  be  weighed  for  the  purpose  of 
deciding  upon  the  location  and  design  of  the  canal  pertain  to  the  exca- 
vation of  the  prism,  the  lining  of  the  bed  and  slopes,  and  the  revetting 
of  the  superbanks. 

Excavation  cost  depends  upon  the  character  of  the  material,  the 
quantities  to  be  moved,  and  the  disposition  which  may  be  made  of  the 
spoils;  all  these,  together  with  the  depth  and  width  of  the  cut,  will 
influence  the  methods  which  secure  the  most  economical  excavation. 
Rock  is  most  cheaply  removed  in  the  dry;  the  principal  operations 
involved  in  excavating  hard  rock,  a  classification  which  includes  those 
formations  which  can  be  excavated  in  large  masses  only  by  the  use  of 
explosives,  are  drilling,  blasting,  loading,  and  disposing. 

Rock  drilling  may  be  done  by  hand  tools  or  by  machine  drills  operated 
by  steam  or  compressed  air;  only  machine  drilling  will  be  here  considered. 


STRUCTURAL   TYPES  243 

This  operation  requires  a  runner  and  helper,  power  being  supplied  from 
a  central  plant.  The  output  varies  with  the  depths  of  the  holes,  being 
from  50  to  60  linear  feet  for  10  and  20  feet  depths  per  shift  of  10  hours. 
To  the  operating  cost  must  be  added  the  power  cost  for  10  horse-power 
per  drill,  the  drill  repairs  and  drill  sharpening;  with  present  wages  drill- 
ing costs  from  10  to  15  cents  per  linear  foot,  depending  on  the  hardness 
of  the  rock  and  the  depth  of  the  holes. 

The  breaking  of  the  rock  for  the  purpose  of  loading  for  removal  requires 
from  1  to  1.5  pounds  of  60  per  cent,  dynamite,  according  to  its  hardness, 
per  cubic  yard  of  output,  and  with  present  cost  of  explosives  a  charge 
of  15  cents  per  cubic  yard  should  be  made  for  blasting.  The  broken  rock 
may  be  loaded  by  hand,  or  machinery,  into  carts,  derrick  or  cable-way 
buckets,  or  dump  cars,  and  the  cost  varies  in  accordance  with  the  method 
employed;  the  output  of  hand  loading  averages  10  cubic  yards  per  man 
per  10-hour  shift,  by  steam  shovel  it  will  be  between  40  and  60  cubic 
yards  per  hour.  Disposal  cost  depends  entirely  upon  the  length  of  haul. 
With  present  wages  rock  excavation  will  cost  from  75  cents  to  $1.50  per 
cubic  yard. 

Earth  is  removed  more  cheaply  by  dredging  than  by  dry  excavation; 
the  cost  of  dredging  will  be  generally  from  15  to  30  cents,  depending  upon 
the  hardness  of  the  material  and  the  distance  of  the  disposal.  Dry  earth 
excavation  may  be  done  by  hand  tools,  horse  and  power  scrapers,  or  by 
steam  shovels,  the  operations  consisting  of  loosening,  loading,  and  dis- 
posing; the  output  and  cost  depend  upon  the  methods  employed,  the 
character  of  the  material,  depth  of  cut,  and  distance  of  haul.  With 
present  wages  the  cost  will  be  from  25  to  50  cents  per  cubic  yard.  Com- 
paratively, the  cost  of  rock  excavation  is  about  three  times  that  of 
earth,  and  dredging  about  0.6  of  earth  excavation.  The  quantity  of 
earth  excavation  is  about  1.2  of  the  flow  area  up  to  the  water  level,  and 
approximately  one-third  of  that  area  for  every  foot  vertical  above 
water  surface. 

Example. — For  a  canal  which  is  to  divert  1000  cub.  sec.  ft.  at  a  velocity 
of  5  ft.  per  sec.  the  quantity  to  be  excavated  to  the  water  level  is  =  200 
X  1.2  =  240  cub.  ft.  per  linear  foot  of  canal,  and  to  a  height  of  5  ft. 
above  the  water  level  it  is  =  240  +  (200  X  1.66)  =  570  cub.  ft.  or  about 
22  cub.  yds. 

For  side-hill  locations  the  quantities  must  be  determined  from  cross- 
sections  taken  at  intervals  of  10  feet. 


244  HYDRO-ELECTRIC   PRACTICE 

The  bed  and  canal  sides  (Fig.  77,  1)  in  rock  location  should  be  finished 
as  smooth  as  practicable,  in  order  to  realize  the  highest  flow  efficiency, 
which  will  generally  require  hand-tool  finishing  of  the  bed,  while  the  sides 
should  be  cut  out  by  channelers,  which  with  present  wages  costs  from 
15  to  18  cents  per  square  foot  surface,  depending  upon  the  hardness 
of  the  rock  and  the  depth  of  the  channel  cut.  In  alluvial  locations  the 
bed  and  canal  slopes  should  be  covered  with  a  lining,  in  order  to  guarantee 
the  permanency  of  the  prism  and  reduce  the  roughness  to  a  minimum 
and  thereby  secure  the  best  flow  efficiency.  Canal  lining  may  be  of  timber 
or  concrete-steel.  Timber  lining  (Fig.  77,  2,  3,  and  4)  consists  of  3-inch 
planking  laid  longitudinally  upon  12  X  12  inch  timber  sills  spaced  8  ft. 
c.  to  c.  and  imbedded  in  the  bed  material,  being  secured  in  place  by  con- 
nection to  bearing  piles  from  8  to  16  ft.  long,  or  by  iron  rods  of  the  type 
described  for  the  lining  of  a  reservoir  embankment  slope  in  Article  73. 
A  lining  of  concrete-steel  (Fig.  77,  5,  6,  and  7)  may  be  laid  upon  transverse 
timber  sills,  as  above,  or  upon  concrete  sills  8  inches  square,  which  need 
no  further  support  unless  the  underlying  material  is  mud,  when  piles 
must  be  driven.  The  concrete  lining  is  6  inches  thick  for  sills  8  ft.  centres, 
and  is  connected  with  the  sills  by  one-inch  dowels  set  4  ft.  c  to  c.  The 
concrete  lining  contains  reinforcing  steel.  The  canal  slopes  should  be 
no  steeper  than  1.5  horizontal  in  one  vertical;  they  may  be  lined  in  the 
manner  described  for  the  bed,  being  structurally  continuous  of  the  bed 
lining  and  terminating,  when  of  timber,  one  foot  below  the  normal  flow 
level  in  a  berme  (shown  in  Fig.  77,  2) ,  and,  when  of  concrete,  2  feet  above 
such  elevation  (as  shown  in  Fig.  77,  5). 

The  superbanks  of  the  canal  should  be  sloped  at  two  horizontal  in 
one  vertical  and  paved. 

Views  7  and  8  show  a  rock  canal  with  channelled  sides  and  paved 
superbanks,  Views  9,  10,  11  an  earth  canal  with  timber  lining. 

From  these  data  estimates  for  various  locations  and  prisms  can 
readily  be  compiled,  and  their  comparative  cost  will  point  to  the  most 
economical. 

Appurtenant  structures  to  diversion  canals  are  those  required  for  the 
safeguarding  of  the  superbanks  against  erosion  from  surface  run-off, 
interception  of  unavoidable  lateral  stream  sources,  the  devices  control- 
ling the  flow  in  the  canal,  and  means  of  overhead  crossings. 

Ordinary  run-off  from  rainfall  is  best  intercepted  by  a  longitudinal 
paved  drain  located  at  the  top  of  the  superbanks,  from  which  laterals 


View  7 


View  8 


Canal  in  Rock 

with   Channelled  Sides 

Completed 


THE 
UNIVERSITY 


View  9 


Canal  in  Earth, 

Timber  lined 

Laying  the  Sills 


H.IUM41 

''H.V.S.* 


View  10 


^^        Timber  lined 
Planking 


If 
3* 


Fig.  77 
Diversion  Canal 


In  Rock 


In  Earth 
Timber  lined 


pgep 
In  Earth 
Concrete  lined 


245 


246  HYDRO-ELECTRIC    PRACTICE 

of  similar  type  are  led  down  the  slopes  at  intervals,  depending  upon  the 
volume  likely  to  accumulate,  of  from  100  to  300  feet.  When  the  canal 
traverses  ravines  which  form  stream  sources  after  heavy  rainfall,  pro- 
vision must  be  made  to  pass  such  flow  under  the  canal  by  means  of  con- 
crete culverts,  unless  the  ravine  can  be  made  part  of  the  diversion  canal 
by  securely  cutting  off  its  terminal  and  connecting  the  canal  banks  with 
those  of  the  ravine;  when  the  volume  which  may  pass  down  the  ravine 
is  likely  to  exceed  0.1  of  the  canal  flow  area,  an  overflow  must  be  con- 
structed in  the  canal  bank  to  pass  the  excess.  Generally  speaking,  it 
will  always  prove  the  safer  practice  to  care  for  such  exterior  flow  sources 
by  passage  under  the  canal,  the  structure  being  of  the  concrete  culvert 
type  and  of  ample  dimensions. 

The  canal  entrance  is  guarded  by  headgates,  which  should  afford 
complete  and  ready  control  of  all  flow  into  the  canal;  they  may  be  of  a 
variety  of  types  as  suggested  by  the  volume  of  the  flow  and  the  operating 
requirements.  Stop-logs,  which  were  described  in  connection  with  the  open 
spillway  in  Article  68,  are  a  simple,  effective,  and  inexpensive  device  for 
headgate  service,  being  placed  and  operated  in  the  same  manner  as  when 
employed  for  the  closing  of  overflow  sluices.  Needles ,  also  described  in  Ar- 
ticle 68,  may  be  used,  or  lift-gates  of  timber  or  steel  framing.  A  foot-bridge 
is  arranged  at  the  headgate  crossing  and  serves  as  an  operating  platform. 
Some  headgate  designs  are  shown  in  Fig.  78  and  in  Views  12,  13,  and  14. 

An  intake  to  the  canal  is  frequently  arranged  above  the  headgates  for 
the  purpose  of  creating  a  readily  accessible  pool  in  which  floatage  can  be 
intercepted  and  prevented  from  passing  into  the  canal ;  it  may  also  be  the 
means  of  securing  a  more  complete  diversion  of  the  low  flow  into  the  canal. 

A  forebay  is  likewise  arranged  at  the  terminal  of  the  canal,  being 
simply  a  gradual  enlargement  in  which  the  velocity  of  the  flow  is  reduced 
before  the  water  enters  the  power  house;  its  dimensions  are  decided  by 
those  of  the  power  house  and  by  the  character  of  the  turbine  installation. 

A  waste  weir  should  be  arranged  near  the  end  of  the  canal,  being 
practically  a  short  open  .spillway  with  one  or  two  overflow  sluices ;  float- 
age, ice,  and  surplus  flow  may  be  passed  over  it. 

Bridges  are  often  required  across  a  canal  for  operating  purposes  and 
to  accommodate  public  traffic. 

Diversion  is  secured  by  flumes  when  the  volume  is  less  than  500 
sec.  ft.  Flumes  are  rectangular  or  elliptical  timber  conduits  of  designs 
and  construction  shown  in  Fig.  79;  they  are  supported  on  timber  trestles 


View  11 


Canal  in  Eartr 
Timber  lined 

Completed 


Canal   Head  Gates 
Stony  Sluices 


OF  THE 

UNIVERSlTv 


View     14. 
Timber    Headgates. 


•~^fv'^"?Frfi'VA)WUgtv-XJa^^^k'J>3<W^^  -  ^wwvwyy^.-.-.'.iixyy.'  •-••.•  \.iyrrrf™f.vfrrf}9VSL\ frr,. 

Front  Elevation 


Ground  Plan 


Fig.  7S 
Canal  Head  Gate 


Detail  of 
Gate  Seat 


H.E.P.144 
H.V.S. 

247 


248  HYDRO-ELECTRIC   PRACTICE 

or  masonry  piers  or  are  placed  on  timber  sills  resting  upon  the  surface 
of  the  ground.  They  should  be  water-tight,  and  their  section  is  best 
confined  to  that  required  for  the  passage  of  the  volume  of  water  to  be 
diverted,  so  that  all  parts  of  the  conduit  remain  in  a  constantly  saturated 
condition.  The  top  should  be  covered  with  removable  planks  to  protect 
the  water  surface  against  the  sun  and  cold.  The  flow  in  flumes  follows 
the  laws  found  for  open  channels.  '  The  flume  entrance  is  guarded  by 
gates  of  stop-log,  needles,  or  lift  type. 

Diversion  in  Pipes. — When  the  volume  to  be  diverted  is  less  than 
500  sec.  ft.,  or  when  the  construction  cost  of  a  canal  or  flume  is  abnormally 
high,  diversion  in  pipes  may  prove  more  economical;  in  high-head  develop- 
ments the  final  passage  of  the  water  to  the  turbines  is  always  through  pipes. 

The  flow  of  water  in  pipes  is  based  upon  the  same  general  theory  as 
that  developed  for  flow  in  open  channels,  in  accordance  with  the  funda- 
mental formula  of  v  =  C  ^  RS,  which  has  been  analyzed  in  Article  75. 
The  sizes  of  pipes  for  diversion  service  will  generally  be  between  2  and  8 
feet  in  diameter,  the  velocities  from  2  to  6  feet  per  second,  and  the  slopes 
from  0.001  to  0.0001. 

TABLE  25.— VALUES  WITHIN  THE  ABOVE  LIMITS  OF  A,  R,  AND  v/R. 

Diameter,  Area,  Hydr.  radius, 

inches.  sq.  ft.  R.  j/R. 

24 3.124  0.500  0.707 

30 4.909  0.625  0.791 

36 7.067  0.750  0.866 

42 9.621  0.875  0.935 

48 12.57  1.0  1.0 

54 15.90  1.125  1.061 

60 19.64  1.25  1.118 

66 22.76  1.375  1.173 

72 28.72  1.50  1.225 

78 33.18  1.625  1.275 

84 38.48  1.75  1.323 

90 44.18  1.875  1.370 

96 50.26  2.0  1.414 

TABLE  26.— DISCHARGE  VOLUME  IN  CUBIC  SECOND  FEET  FOR  VARI.OUS  SIZE  PIPES 

AND  VELOCITIES. 

Diameter,  inches. 

24 

30 

36 

42 

48 

54.. 


2 

2.5 

3 

3.5 

4 

4.5 

5 

5.5 

6ft.  p.  sec. 

6.3 

7.8 

9.4 

11.0 

12.5 

14.1 

15.7 

17.3 

18.8 

9.8 

12.3 

14.7 

17.2 

19.6 

22.1 

24.5 

27.0 

29.4 

14.1 

17.6 

21.2 

24.7 

28.3 

31.7 

35.3 

38.8 

42.3 

19.2 

24.0 

28.8 

33.6 

38.4 

43.2 

48.0 

52.8 

57.6 

25.1 

31.4 

37.7 

44.0 

50.2 

56.5 

63.8 

69.1 

75.4 

31.8 

39.7 

47.7 

55.6 

63.6 

71.5 

79.5 

87.4 

95.4 

rWedge  Space  ^Double  Wedge 


Fig.  79 

Flumes  and  Trestles 


Tongue  and  Groove 
Detail 


Side  Elevation 
of  Plume 


Trestle 


249 


250 


HYDRO-ELECTRIC   PRACTICE 


TABLE  26.— DISCHARGE  VOLUME  IN  CUBIC  SECOND  FEET  FOR  VARIOUS  SIZE  PIPES 

AND  VELOCITIES.— Continued. 


Diameter,  inches. 
60  

2 

39.3 

2.5 
49.1 

3 
58.9 

3.5 
68.7 

4 

78.5 

4.5 

88.4 

5 
98  2 

5.5 
108  2 

6ft.  p.  sec. 
117  8 

66  

47.5 

59.4 

71.3 

83.2 

95.0 

106.9 

118.8 

130  7 

142  5 

72  

56.5 

70.7 

84.8 

98.9 

113.5 

127.6 

141  8 

156  0 

170  2 

78  

.  .     66.4 

82.9 

99.5 

116.1 

132.7 

1493 

165  9 

182  5 

199  1 

84  

76.9 

96.2 

115.4 

134.7 

153.9 

173.2 

1924 

211  6 

230  9 

90.. 

88.3 

110.4 

132.5 

154.6 

176.7 

198.8 

220.9 

2430 

2fi5  1 

96 100.5     125.6     150.8     175.9     201.0     226.2     251.3     276.4     301.5 

The  value  of  "C"  has  been  established  by  observations  and  experi- 
ments of  flow  in  pipes,  and  is  a'ccepted  as, 

for  smooth  concrete  pipes  of  ten  years'  service,      C  =  120, 
for  wooden  stave  pipes  of  ten  years'  service,  C  =  115, 

for  steel  plate,  riveted  pipes  of  ten  years'  service,  C  =  110. 
Tables  27,  28,  and  29  give  velocities  for  values  of  R,  represented 
by  diameter  of  pipe,  and  of  S,  for  the  above  three  expressions  for  C. 

TABLE  27.— VELOCITIES  WHEN  C  =  110. 


liameter,  inches. 

.0001 

.0002 

.0003 

.0004 

.0005 

.0006     .0007 

.0008 

.0009 

.001  =  S. 

24  

0.78 

1.08 

1.35 

1.56 

1.74 

1.91 

2.06 

2.20 

2.34 

2.46 

30  

0.89 

1.22 

1.54 

1.78 

1.98 

2.18 

2.35 

2.51 

2.67 

2.80 

36  

0.95 

1.33 

1.64 

1.90 

2.43 

2.32 

2.50 

2.69 

2.85 

3.00 

42  

1.02 

1.44 

1.77 

2.04 

2.28 

2.50 

2.72 

2.88 

3.06 

3.23 

48  

1.10 

1.56 

1.01 

2.20 

2.46 

2.70 

2.93 

3.11 

3.30 

3.48 

54  

1.16 

1.65 

2.01 

2.32 

2.59 

2.83 

3.09 

3.28 

3.48 

3.67 

60  

1.23 

1.74 

2.13 

2.46 

2.75 

3.01 

3.28 

3.47 

3.69 

3.89 

66  

1.20 

1.82 

2.24 

2.58 

2.88 

3.16 

3.44 

3.64 

3.87 

4.08 

72  

1.34 

1.90 

2.33 

2.64 

3.00 

3.27 

3.60 

3.78 

4.02 

4.25 

78  

1.40 

1.98 

2.44 

2.80 

3.14 

3.43 

3.76 

3.96 

4.20 

4.44 

84  

1.45 

2.05 

2.53 

2.90 

3.23 

3.55 

3.84 

4.10 

4.35 

4.57 

90  

1.50 

2.12 

2.60 

3.00 

3.35 

3.67 

4.01 

4.24 

4.50 

4.74 

96  

1.55 

2.19 

2.66 

3.12 

3.46 

3.79 

4.16 

4.38 

4.65 

4.91 

TABLE  28.—  VELOCITY  WITH  C 

=  115 

Diameter. 

.0001 

.0002 

.0003 

.0004 

.0005 

.0006 

.0007 

.0008 

.0009 

.001 

24  

0.81 

1.14 

1.40 

1.62 

1.81 

1.98 

2.13 

2.29 

2.43 

2.56 

30  

0.91 

1.28 

1.57 

1.82 

2.03 

2.22 

2.40 

2.57 

2.73 

2.87 

36  

1.00 

1.41 

1.73 

2.00 

2.24 

2.44 

2.65 

2.83 

3.00 

3.16 

42  

1.07 

1.51 

1.85 

2.14 

2.40 

2.61 

2.85 

3.06 

3.21 

3.40 

48  

1.15 

1.63 

1.99 

2.30 

2.57 

2.80 

3.06 

3.29 

3.45 

3.65 

54  

1.22 

1.73 

2.11 

2.44 

2.73 

2.96 

3.25 

3.50 

3.66 

3.87 

60  

1.28 

1.81 

2.19 

2.56 

2.86 

3.12 

3.42 

3.65 

3.84 

4.06 

66  

1.35 

1.91 

2.32 

2.70 

3.02 

3.30 

3.59 

3.85 

4.05 

4.27 

72  

1.41 

1.99 

2.43 

2.82 

3.15 

3.44 

3.75 

4.05 

4.24 

4.46 

78  

1.46 

2.07 

2.51 

2.92 

3.28 

3.57 

3.90 

4.20 

4.38 

4.63 

84  

1.52 

2.15 

2.61 

3.00 

3.40 

3.71 

4.07 

4.40 

4.66 

4.82 

90  

1.54 

2.23 

2.72 

3.14 

3.50 

3.83 

4.17 

4.50 

4.71 

4.95 

96  

1.62 

2.29 

2.80 

3.24 

3.64 

3.94 

4.35 

4.66 

4.86 

5.15 

STRUCTURAL   TYPES  251 

TABLE  29.— VELOCITY  WITH  C  =  120. 


Diameter. 
24  

.0001 
0.93 

.0002 
1.30 

.0003 
1.61 

.0004 
1.86 

.0005 

2.07 

.0006 
2.28 

.0007 
2.45 

.0008 
2.63 

.0009 
2.79 

.001 
2.94 

30  

1.07 

1.52 

1.85 

2.14 

2.40 

2.62 

2.83 

3.02 

3.21 

3.38 

36  

1.14 

1.61 

1.95 

2.28 

2.55 

2.79 

3 

.00 

3.22 

3.42 

3.60 

42  

1.22 

1.73 

2.10 

2.40 

2.73 

2.98 

3 

.26 

3.43 

3.66 

3.82 

48  

1.32 

1.87 

2.25 

2.64 

2.95 

3.22 

3 

.50 

3.74 

3.96 

4.17 

54  

1.39 

1.97 

2.40 

2.78 

3.10 

3.40 

3 

.69 

3.95 

4.17 

4.39 

60  

1.48 

2.10 

2.56 

2.96 

3.32 

3.62 

3 

.93 

4.21 

4.44 

4.68 

66  

1.55 

2.19 

2.68 

3.10 

3.52 

3.80 

4 

.10 

4.42 

4.65 

4.90 

72  

1.60 

2.26 

2.76 

3.20 

3.58 

3.92 

4, 

.25 

4.58 

4.80 

5.06 

78  

1.68 

2.38 

2.90 

3.36 

3.76 

4.11 

4.45 

4.80 

5.04 

5.31 

84  

1.74 

2.46 

3.00 

3.48 

3.90 

4.26 

4 

.62 

4.98 

5.22 

5.50 

90  

1.80 

2.55 

3.10 

3.60 

4.03 

4.41 

4 

.76 

5.12 

5.40 

5.69 

96  

1.86 

2.65 

3.22 

3.72 

4.16 

4.55 

4 

.94 

5.30 

5.58 

5.88 

Location,  kind  and  size  of  pipe  are  to  be  determined  when  planning 
a  pipe  line;  velocity  and  slope  are  fixed  by  the  volume  to  be  diverted 
and  the  diameter  of  the  pipe. 

The  location  of  a  diversion  pipe  line  is  to  be  chosen  to  secure  the 
economically  shortest  in  distance  while  insuring  the  preservation  of  the 
pipe.  Any  kind  of  pipe  wears  longer  if  lying  entirely  above  the  surface 
of  the  ground  with  air  freely  circulating  all  around  it;  it  can  then  be 
readily  examined,  repainted,  and  kept  in  proper  condition;  therefore, 
if  avoidable,  pipe  should  not  be  wholly  or  partially  buried.  Thorough 
underdraining  should  be  provided,  so  that  no  water  will  accumulate 
beneath  it  at  any  point. 

In  Fig  80  the  straight  line  In,  connecting  the  upper  and  lower  pool 
surfaces,  is  the  hydraulic  gradient',  no  part  of  the  pipe  line  should  rise 
more  than  25  feet  above  this  gradient,  but  may  otherwise  vary  in  eleva- 
tions and  grades.  The  pipe  must  be  anchored  at  intervals  of  50  feet  to 
concrete  benches,  shown  in  Fig.  80,  2,  their  dimensions  depending  upon 
the  character  of  the  material  in  which  they  must  be  placed  and  size 
and  slope  of  pipe;  the  pipe  proper  is  connected  to  the  supporting  struc- 
tures by  steel  rods  fastened  to  steel  collars  around  the  pipe;  the  rods 
should  have  turnbuckles  to  compensate  for  temperatures,  that  is  extreme 
heat  or  cold;  this  device  is  shown  in  Fig.  80,  3.  By  the  aid  of  Tables 
27,  28,  and  29  all  problems  of  flow,  discharge,  and  slope  can  be  readily 
solved. 

Example. — Required  the  diversion  of  80  cubic  second  feet,  total 
head  400  ft.  Only  steel  plate  pipe  is  available  under  such  a  head. 
C  =  110. 


252  HYDRO-ELECTRIC   PRACTICE 

From  Table  26  find  the  size  and  velocity  to  yield  the  required  discharge: 
in  a  54-inch  pipe  with  a  velocity  of  5  ft.  discharge  is  79.5  cub.  sec.  ft., 
in  a  60-inch  pipe  with  a  velocity  of  4  ft.  discharge  is  78.5  cub.  sec.  ft., 
in  a  66-inch  pipe  with  a  velocity  of  3.5  ft.  discharge  is  83.2  cub.  sec.  ft., 
and  from  Table  37  find  S  for  66-inch  pipe  and  3.5  ft.  velocity  =  .0003. 
If  a  smaller  size  pipe  is  preferred,  R  is  found  from  Table  25,  say  for 

54-inch  pipe  V  R  =  1.061,  then  from  V  =  C  y  RS,  and 

V  -T-  C  V  S  =  V  S,  or  5  •*-  110  X  1.061  =  V  S 
(5  -T-  116.710)2  =  VS,  or  S  =  0.0019. 

The  question  of  recommendable  size  of  pipe  is  to  be  determined  from 
balancing  the  excess  pipe  cost  and  the  net  earning  value  of  the  head 
represented  by  the  difference  in  slope  between  the  two  sizes  of  pipe 
compared. 

Example. — For  the  requirements  of  the  last  example,  the  line  is  3500 
feet  long;  66-inch  pipe  costs  $2.00  per  linear  foot  more  than  the  54-inch 
pipe,  the  excess  cost  of  the  larger  size  pipe  is  therefore  $7000.00;  the 
difference  in  head  will  be  0.0019  —  0.00073  or  0.00127  X  3500,  being 
4.09  feet,  which,  with  a  flow  of  80  cub.  sec.  ft.,  represents  about  26.2 
electrical  horse-power  (consult  Diagram  3).  If  the  net  value  of  the 
current  is  $15.00  per  horse-power  per  year,  the  amounts  to  be  balanced 
against  each  other  are 

interest  at  5  per  cent,  on  excess  pipe  cost  of  $7000.00    =  $350.00, 
and  net  receipt  from  power  represented  by  4.09  feet  h  =    393.00; 

in  other  words,  the  value  of  the  head  saved  is  greater  than  the  interest 
on  the  investment  and  therefore  the  larger  size  pipe  is  recommendable. 

The  difference  of  first  cost  of  the  three  types  of  pipes  is  small;  the 
concrete-steel  pipe  is  imperishable  and  calls  for  no  maintenance  expendi- 
tures ;  wooden  stave  pipe  wears  as  well  as  does  steel  plate  pipe,  provided 
it  is  kept  filled  with  water  at  a  uniform  pressure  at  all  times;  steel  pipe 
requires  recoating  every  third  year. 

The  flow  in  pipes  is  controlled  by  valve  gates  of  different  types,  which 
are  placed  at  the  intake,  which  latter  must  also  be  guarded  by  a  trash 
rack,  consisting  of  flat  iron  bars  set  in  an  iron  frame,  half  inch  centres, 
and  secured  to  the  pipe  intake.  Such  an  arrangement  is  shown  in  Fig.  81. 


Fig.  80 

Pipe  Line 
and  Details 


v\xj  L  tcO<xx-'NxX?g^^.glXp^ 


253 


254 


HYDRO-ELECTRIC    PRACTICE 


ARTICLE  76. — The  diversion  terminates  at  the  power  house.  The 
location  of  this  structure  is  determined  as  fully  discussed  in  connection 
with  the  topic  of  development  programmes  in  Article  48.  Its  type  de- 
pends primarily  upon  the  head.  For  low-head  developments  it  will 
generally  be  located  at  the  spillway  or  closely  below  it;  with  a  medium 
head,  from  30  to  60  feet,  the  power  house  may  be  at  the  spillway  or  at 


Fig.  81 

Intake  Gate  Valve 
and  Trash  Rack 


the  end  of  the  diversion  works;  while  for  high-head  developments  it 
will  always  be  at  the  terminal  of  a  pressure  line.  Generally  speaking, 
the  location  should  be  selected  with  a  view  to  secure  a  good  foundation, 
unobstructed  efflux  of  the  water, — that  is,  unimpeded  by  the  overfall 
from  the  spillway,  islands,  rocks,  or  shoals, — convenient  access  to  the 
building  for  conveyance  of  the  equipment,  protection  against  flood  rise, 
ice,  and  logs,  and,  if  practicable,  the  power  house  should  be  on  the  side 
of  the  river  where  the  transmission  line  leads  out. 

The  foundation  considerations  are  the  same  as  those  described  for 
the  spillway,  as  the  power  house,  in  a  sense,  fulfils  the  functions  of  a 


STRUCTURAL   TYPES  255 

dam;  the  arrangement  and  construction  of  the  power-house  foundation 
are,  therefore,  similar  to  those  outlined  in  Article  56  and  the  approximate 
quantities  of  material  as  given  in  Diagram  12.  Here,  as  in  the  spillway 
case,  the  cutting-off  of  substrata,  by  which  water  might  pass  under  the 
foundation,  is  of  vital  importance;  in  fact  the  power-house  foundation 
in  an  alluvial  location  is  best  entirely  surrounded  by  a  substantial  cut-off 
wall,  the  foundation  proper  overhanging  the  cut-off  at  least  three  feet. 
The  sliding  of  the  structure,  under  the  pressure  from  the  upper  level 
water,  must  be  likewise  considered  and  guarded  against,  and  an  apron 
should  be  placed  along  the  entire  downstream  side,  being  from  8  to  16 
feet  wide  according  to  the  depth  of  the  water  in  the  tail-race. 

For  plans  of  power-house  foundation  reference  may  be  made  to 
Plan  18,  illustrating  those  for  spillways.  View  15  shows  the  foundation 
of  a  power  house  in  an  alluvial  location,  consisting  of  bearing  piles,  a 
timber  grillage  secured  to  them,  and  concrete  placed  between  grillage 
frame  and  upon  it.  This  was  completely  enveloped  by  a  cut-off  con- 
sisting of  sheet  piling  and  concrete  wall. 

The  substructure  of  the  power  house,  Fig.  82,  elevates  the  station 
above  the  lower  pool,  supports  it,  and  forms  the  pits  into  which  the 
water  from  the  turbines  is  discharged  and  by  which  it  passes  into  the 
tail-race  or  directly  into  the  lower  pool.  Power-house  substructures  are 
of  practically  one  type,  rectangular  in  plan,  the  length  depending  upon 
the  number  of  power  units,  from  12  to  18  feet  for  each,  according  to  the 
size  of  turbines,  and  the  width  conforming  to  that  of  the  superstructure. 
The  substructure  consists  of  the  forebay  wall,  Fig.  82,  1,  which  extends 
along  the  upstream  side  and  must  resist  earth  or  hydrostatic  pressures 
and  supports  the  upper  portion  of  the  station,  the  end  walls,  Fig.  82,  2, 
also  resisting  lateral  pressures  and  supporting  the  station  building,  the 
pit  walls  by  which  the  different  chambers  are  separated  from  each  other 
and  which  must  be  designed  for  lateral  pressure  on  one  side  in  the  event 
of  the  adjacent  pit  being  unwatered;  the  pit  floors  and  the  pit  roof 
complete  the  substructure.  The  walls  may  be  of  masonry,  monolithic 
or  block  concrete,  the  floor  and  roof  of  concrete  or  concrete-steel.  The 
substructure  is  therefore  enclosed  by  walls  except  on  the  downstream  ends, 
Fig.  82,  4,  and  these  are  arranged  for  the  reception  of  gates  or  stop  logs 
to  enable  the  emptying  of  any  of  the  pits.  The  height  of  the  substructure 
is  regulated  by  the  water  level  in  the  lower  pool,  but  the  depth  of  water 
in  the  pits  at  the  lowest  level  should  not  be  less  than  five  feet,  as  there 


256 


HYDRO-ELECTRIC    PRACTICE 


should  be  a  four-feet  water  cushion  below  the  discharge  ends  of  the  draft 
tubes.  There  is  no  objection  that  the  highest  lower  pool  water  should 
stand  at  the  under  side  of  the  pit  roof. 

View  16  shows  such  a  power-house  substructure  as  here  described, 
and  which  may  be  termed  a  standard  type ;  it  is  placed  upon  the  founda- 
tion shown  in  View  15,  this  being  the  upstream  elevation,  while  View  17 


Fig.  82 

Power  House 
Substructure 

H.E.P.151 
H.V.S. 


Longitudinal  Section        _ 


Transverse  Section 


is  of  the  downstream  side.  In  this  case  the  walls  are  all  constructed  of 
concrete  blocks  three  feet  thick,  tongued  and  grooved  all  around ;  the  floor 
and  roof  are  of  concrete-steel. 

The  superstructure  houses  the  power  equipment,  and,  depending 
upon  the  head,  may  be  arranged  for  drowned  or  dry  turbine  installa- 
tion. In  the  first  case,  Fig.  83,  the  turbines  are  placed  in  isolated  bays 
into  which  the  water  enters  freely  with  the  upper  level  elevation,  and 
passes  through  the  turbines  into  the  pit  below;  the  pit  roof  forms  the 
turbine-bay  floor.  The  width  and  length  of  the  turbine  bays,  Fig.  83,  1, 
are  regulated  by  the  installation  space  required  for  the  turbines,  gener- 


View  15 


Power  House  Foundation 


H.v.S. 


View  16 


Power  House  Substructure 
Up  stream  View 


View  17 


Power  House    Substructure 
Down  stream  Elevation 


H.E.P.156 
H.V.S. 


Power  House     Superstructure 
Up  stream  Elevation 


View  18a 


H.E.P.157 
H.V.S. 


Power  House  Up  stream  View 


View  19 


rower  House  Superstructure 
Down  stream  Elevation 


STRUCTURAL   TYPES 


257 


ally  from  10  to  18  feet  wide  and  from  15  to  40  feet  long;  their  height  is 
controlled  by  the  upper  level.  The  side  walls  or  partitions,  Fig.  83,  2, 
are  best  constructed  of  concrete-steel,  and  must  be  designed  to  resist 
lateral  hydrostatic  pressure  existing  when  the  adjacent  bay  is  unwatered. 
The  downstream  end  of  the  turbine  bay,  Fig.  83,  3,  is  closed  by  a  masonry 
or  concrete  wall  or  a  steel-plate  bulkhead  of  semicircular  design  with  a 


Fig.  83 
Power  House 
Turbine  Bays 


Longitudinal  Section     4 


H.E.P.152 
H.V.S. 


radius  equal  to  half  the  width  of  the  bay  and  secured  to  the  floor  and 
partitions;  either  of  these  must  resist  the  hydrostatic  pressure  due  to  the 
upper  level  head.  The  partition  tops,  Fig.  83,  4,  are  connected  by  steel 
members,  concrete-steel  beams  or  arches. 

Views  18  and  19  are  of  superstructures  of  this  standard  type  placed 
upon  the  substructure  shown  in  Views  16  and  17.  The  bays  are  dimen- 
sioned to  accommodate  a  line  of  four  horizontal  turbines;  the  head  is  20 
feet.  In  this  plant  the  steel-plate  bulkhead  was  first  introduced ;  a  separate 
view  of  this  from  the  downstream  side  is  given  in  View  20.  All  the  views 
from  7  to  20  are  of  the  hydro-electric  plant  at  Sault  Ste.  Marie,  Mich., 

17 


258  HYDRO-ELECTRIC    PRACTICE 

which  was  designed  by  the  author  and  constructed  under  his  supervision 
(1897  to  1902). 

For  medium  or  high-head  developments  the  superstructure  of  the 
power  house  simply  becomes  a  building  in  which  the  equipment  is  placed, 
consisting  of  a  floor,  being  the  pit  roof,  and  of  suitable  walls  and  roof; 
the  turbines  are  encased,  water  being  supplied  to  them  by  pipes  or 
penstocks  and  discharged  into  the  pit.  It  is  to  be  deplored  that  little 
if  any  thought  is  generally  bestowed  upon  the  architectural  appearance 
of  the  power-house  superstructure;  as  a  rule,  it  is  of  the  character  of 
the  plainest  factory  structure;  castellated  tops  or  a  heavy  end  tower 
would  be  entirely  in  harmony  with  the  building's  purpose  and  give 
it  a  most  pleasing  appearance;  in  this  respect  some  of  the  hydro- 
electric power  houses  on  the  European  continent  may  well  be  taken  as 
models. 

This  discussion  of  power-house  types  is  well  illustrated  by  the  fol- 
lowing standard  designs  adapted  to  different  heads  and  installations. 
These  were  all  prepared  by  the  author  in  connection  with  different  pro- 
jects and  some  of  them  have  been  constructed. 

Fig.  84  shows  section  and  elevation  of  a  power  house  adapted  to 
the  lowest  head.  When  less  than  12  feet  is  available,  turbines  are  best 
placed  on  vertical  shafts,  as  there  is  not  sufficient  head  to  drown  them, 
the  water  depth  above  them  should  not  be  less  than  four  feet,  and  the 
vertical  depth  of  the  turbine  runner  is  about  half  of  its  diameter.  The 
foundation  is  indicated  by  No.  2  in  the  figure,  the  pit  by  No.  1,  turbine 
bay  No.  6,  pit  walls  No.  4,  bay  partitions  No.  7,  pit  roof  No.  6,  bulkhead 
wall  No.  8,  turbine  No.  5,  and  generator  No.  9.  The  water  enters  freely 
into  the  turbine  bay  and  flows  out  of  the  pit.  The  generator  in  this 
case  is  directly  coupled  to  the  vertical  turbine  shaft,  being  of  what  is 
known  as  the  umbrella  type,  and  is  placed  on  a  floor  arranged  above 
the  turbine  bay,  supported  by  the  partitions  and  the  bulkhead  wall. 
Note  the  depression  in  the  pit  below  the  turbine,  by  which  the  necessary 
four-foot  water  cushion  is  secured  without  carrying  the  entire  pit  to  that 
depth,  which  represents  some  saving  in  cost.  The  foundation  is  the 
standard  pile-bearing  type  with  upstream  and  downstream  aprons. 
This  type  of  power-house  design  is  available  for  all  low-head  situations, 
the  installation  being,  however,  most  frequently  gear  connected,  as 
umbrella-type  generators  do  not  as  yet  form  standard  electric  equipment 
in  this  country,  though  they  are  being  used  now  more  frequently  in 


Generators 

Direct 
connected 


Fig.  84 
Power  House 

low  head 

Vertical  Turbines 

Drowned 


Section 


i  I!  :? 


levation 

H.E.P.160 
H.V.S. 


259 


260  HYDRO-ELECTRIC    PRACTICE 

Europe  than  the  horizontal  shaft  installation,  securing  higher  efficiency 
of  output.  The  Niagara  Falls  plant  is  so  equipped. 

Fig.  85  shows  the  design  for  a  power  house  with  low  head  in  which 
the  turbine  bay  is  arranged,  outside  of  the  power  building  proper,  in  the 
forebay.  This  type  is  met  with  frequently  in  the  older  plants;  it  pos- 
sesses no  advantages  nor  represents  economies  over  the  one  described  in 
this  article;  as  a  matter  of  fact  it  adds  to  the  masonry  construction. 
The  installation  here  shown  is  of  a  double  horizontal  turbine  drowned, 
the  turbine  bay  being  closed  downstream  by  a  masonry  bulkhead  with 
a  cast-iron  head  through  which  the  turbine  shaft  passes;  the  exit  from 
the  pit  is  in  a  longitudinal  direction  to  escape  interference  to  free  outflow 
caused  by  the  overfall  from  spillway. 

In  Fig.  86  will  be  recognized  the  standard  low-head  design  heretofore 
described,  being  the  arrangement  of  the  plant  at  Sault  Ste.  Marie,  Mich. 
The  turbine  installation  consists  of  two  pairs  of  horizontals;  as  many 
as  four  pairs  of  wheels  have  been  thus  arranged.  Note  the  closing 
of  the  downstream  end  of  the  turbine  bay  by  the  steel-plate  bulk- 
head and  compare  it  with  the  masonry  bulkhead  on  the  design  of 
the  previous  plant;  the  cost  is  about  one-third  and  much  valuable 
space  is  saved. 

Fig.  87  represents  a  design  which  is  much  used  in  Europe,  in  which 
the  turbine  installation  is  of  the  serial  type,  utilizing  fluctuating  heads 
with  equal  efficiencies.  The  design  differs  chiefly  from  those  described 
in  the  arrangement  of  the  pit,  the  discharge  being  from  two  levels  as  the 
fluctuations  of  the  upper  and  lower  pools  may  require.  The  turbines 
can  be  only  of  the  vertical  type,  and  abroad  the  generators  are  generally 
direct  connected.  This  design  should  be  used  much  more  frequently 
than  it  is  in  this  country,  especially  on  the  rivers  in  the  South  which  are 
subject  to  great  fluctuations.  The  foundation  is  represented  by  No.  2 
of  the  figure,  the  pit  by  No.  1,  the  turbine  bay  by  No.  5;  3,  6,  and  8  are 
practically  bulkheads,  6  being  depressed  downward  to  make  water  seal 
with  lower  level  at  C.  The  installation  consists  of  a  double  vertical  tur- 
bine, 13  and  14,  the  first  discharging  upward,  the  latter  downward,  and 
a  third  vertical  wheel,  No.  12,  also  discharging  downward;  12  and  13 
use  the  upper  pit  channel;  14  the  lower.  The  water  enters  wheels  13 
and  14  at  15;  11  is  a  water  thrust  bearing;  10  is  the  generator;  16  is 
a  stop-log  gate  closing  the  entrance  to  the  turbine  bay.  There  is  noth- 
ing complicated  about  this  design  nor  is  it  one  of  greater  cost  than  the 


85 


Power  House 

low  head 
horizontal  Turbines 

drowned  in 
forebay 


H.E.P.161 
H.V.S. 


261 


Fig.  86 
Power  House 

for    low    head    and 

horizontal    turbines 

Drowned . 


Generators 
direct 

connected 


Up  Stream 
elevation 


Down  Stream 
elevation 


3PKT 

'^""Elev.5 


H.E.P.162 
H.V.S. 


262 


Fig.  87 
Power  House 

fluctuating  head 
Serial  Turbines 


263 


264  HYDRO-ELECTRIC   PRACTICE 

others,  while  it  represents  the  only  plan  by  which  an  efficient  output 
can  be  secured  from  a  fluctuating  head. 

Fig.  88  represents  the  general  practice  for  low  head,  the  installation 
being  of  double  verticals  discharging  by  union  draft  tube.  No.  1  is  the 
pit,  No.  5  the  turbine  bay,  13  and  14  the  turbines,  11  the  thrust  bearing, 
and  15  the  generator;  3  and  6  show  the  forebay  wall,  8  the  bulkhead. 

Fig.  89  represents  the  general  type  of  power  house  for  medium-head 
developments;  foundation,  pit,  and  operating  floor  are  the  constituent 
parts,  and  little  variety  is  called  for.  No.  1  shows  the  pit,  of  the  same 
design  and  construction  as  in  the  standard  low-head  type,  unless  for 
high  heads,  when  the  accompanying  pressures  must  be  properly  provided 
for.  The  supply  pipe  enters  through  the  house  wall,  terminating  in  the 
turbine  case,  from  which  the  water  escapes  by  the  draft  tube. 

This  same  arrangement  answers  for  the  highest  heads. 

Power-house  designing,  in  the  author's  judgment,  follows  too  much 
in  old  established  routes.  As  the  focus  and  realization  of  an  enterprise 
comparing,  in  point  of  investment  and  earning  value,  well  with  the  most 
important  of  other  lines,  it  deserves  the  greatest  amount  of  care.  There 
is  a  tendency  to  overdo  the  heavy  dimensioning  of  walls  and  allot  un- 
necessarily large  areas  for  the  equipment  installation;  this  would  be 
avoided  if  each  part  of  the  structure  were  independently  designed  for  the 
duties  it  is  to  fulfil.  Just  as  the  spillway  or  a  retaining  wall  is  designed, 
so  should  the  forebay,  pit  and  end  walls,  turbine  bay,  partitions,  floors, 
and  roof  be  carefully  and  individually  designed,  and  the  space  required 
for  the  electric  equipment  should  be  laid  down  from  the  known  dimensions 
of  floor  frames  and  what  is  required  for  convenient  operating  space; 
anything  more  than  this  becomes  an  expensive  superfluity,  as  it  entails 
more  yardage  in  every  wall,  more  roof  and  floor  areas,  and  other  costly 
excesses  over  what  is  necessary  for  the  purpose. 

A  desire  to  incorporate  in  a  power-house  design  the  elements  of  high- 
est obtainable  efficiency  with  economy  of  cost  of  construction  and  main- 
tenance led  the  author  to  develop  a  power-house  design  where  the  interior 
of  a  gravity  spillway  may  be  utilized  as  the  power  station,  and  by  which, 
it  is  believed,  these  ideals  can  be  secured  under  proper  conditions.  This 
design  is  described  in  detail  and  illustrated  in  Article  78  of  this  part. 

ARTICLE  77.  Appurtenances  to  the  Power  House. — At  the  entrance  of 
the  turbine  bays  trash  racks  are  placed  to  intercept  all  floatage.  They 
generally  consist  of  flat  steel  bars  arranged  closely  to  form  a  rack  held  in 


Fig,  88 
Power  House 

for  low  head  and 
double  vertical 

Turbines  drowned 


H.E.P.164 
H.V.S. 


265 


266  HYDRO-ELECTRIC   PRACTICE 

a  suitable  frame;  the  latter  is  secured  to  the  structure  so  that  it  inclines 
downstreamward ;  this  general  arrangement  is  shown  in  Fig.  90;  the 
details  depend  upon  the  height  of  the  water  and  the  width  of  the  turbine- 
bay  entrance. 

There  is  not  much  latitude  of  design  in  trash  racks.  They  should 
be  amply  strong,  and  in  this  regard  the  winter  conditions,  as  to  anchor 
or  float  ice  accumulations,  must  be  well  understood;  the  former  will 
be  treated  specifically  later  on.  An  operating  platform  is  required  above 
the  trash  rack  so  that  it  can  be  conveniently  raked  and  the  floatage  dis- 
posed of. 

The  upstream  turbine-bay  entrance  and  the  downstream  pit  ends 
are  arranged  to  be  closed  temporarily  for  the  purpose  of  unwatering 
either  chamber  and  rendering  them  accessible  for  repairs  to  equipment, 
etc.  There  are  a  variety  of  devices  used  for  this  purpose,  but,  as  in  the 
case  of  open  spillway  or  other  parts  where  gates  are  required,  the  author 
favors  the  simplest  arrangement,  such  as  stop-logs  or  needles,  which  are 
readily  handled  and  quickly  renewed;  no  other  device,  unless  compli- 
cated and  costly,  can  be  operated  more  conveniently  and  cheaply  than 
stop-logs.  These  have  been  fully  described  in  Article  70. 

A  traveller  is  frequently  provided  in  the  power  house  for  the  handling 
of  the  equipment;  it  is  placed  overhead  in  the  operating  or  generator 
room  and  equipped  for  electric  operation. 

A  machine  shop  or  repair  room  should  always  be  set  aside  in  the 
power  house.  Oil  and  waste  stocks  should  not  be  kept  in  the  operating 
room. 

ARTICLE  78.  The  Submerged  Power-House  Design.  —  The  gravity 
spillway  type  is  analyzed  and  a  standard  design  for  it  detailed  in  Article 
67.  From  this  will  be  noted  that  one  of  the  distinct  features  of  this  type, 
as  compared  with  other  spillways,  is  the  fact  that  there  remains  a  spacious 
interior  enclosed  by  the  walls  forming  the  spillway,  which,  of  necessity  to 
serve  their  purpose,  must  be  safe  against  rupture  and  must  further  be 
absolutely  water-tight,  both  conditions  which  render  this  interior  space 
safe  and  suitable  for  utilization  of  some  purpose  or  other,  and  why  not 
to  place  the  turbines  and  the  generators  therein  and  operate  them? 

As  has  been  emphasized  on  different  occasions  in  this  volume,  it  is 
highly  desirable  that  the  power  house  be  located  close  to  the  spillway, 
so  that  the  conversion  of  the  natural  energy  into  useful  work  may  be 
carried  on  in  closest  proximity  to  the  origin  of  the  natural  forces,  which 


Section 


Fig.  89 

Power  House 

medium  head 

Horizontal  Turbines 

Cased 


Elevation 


H.E.P.165  Sg 
H.v,S. 


268 


HYDRO-ELECTRIC   PRACTICE 


is  at  the  spillway,  unless  in  the  case  of  the  necessity  of  a  diversion  pro- 
gramme. It  is  the  aim  of  all  industrial  enterprises  to  locate  as  near  as 
practicable  to  the  point  of  raw  material;  that  is  exactly  the  case  here, 
as  it  costs  as  much  (and  generally  more)  to  transport  water  and  head 
as  any  other  class  of  staples;  not  only  is  it  a  costly  undertaking,  but, 
much  more  to  the  point,  it  is  a  wasteful  process,  this  transporting  water 


Section 
Details  of  Rack 


for  any  distance  from  the  spillway  to  the  power  house,  as  water  does 
not  move  unless  fall  or  head  is  expended  and  that  is  lost  forever. 
The  spillway  has  a  secure  foundation,  and  it,  with  the  walls,  practically 
forms  a  house,  excepting  that  it  is  not  of  the  conventional  shape;  its 
walls  incline  toward  each  other  and  jointly  form  the  roof;  at  any  rate, 
it  represents  a  substantial  structure,  and  if  it  is  sufficiently  roomy 
there  is  no  reason  why  it  could  not  be  utilized  for  the  purpose  of  a 
power  station.  The  question  of  dimensions  is  readily  determined  when 
the  fall  and  power  output  are  known.  Generally  speaking,  the  submerged 
power  house  can  be  arranged  when  the  fall  exceeds  25  feet  and  the  flue- 


STRUCTURAL   TYPES  269 

tuations  of  river  stage  remain  within  five  feet;  the  output  does  not 
generally  put  a  limitation  on  the  use  of  this  design,  as  the  entire  spill- 
way length  is  available. 

Fig.  91  shows  the  general  arrangement,  which  can  be  varied  to  suit 
different  conditions. 

In  the  section  No.  1  shows  the  walls  of  the  spillway,  the  deck  and 
apron  and  crown;  one  of  the  partitions  arranged  transversely  of  the 
spillway  structure,  as  appears  more  plainly  in  the  partial  elevation  and 
longitudinal  section;  these  partitions,  or  they  may  take  the  form  of  steel 
frames,  need  not  occupy  the  entire  transverse  space  from  deck  to  apron, 
their  central  portions  can  be  omitted,  leaving  an  arch  opening,  which, 
if  need  be,  reinforced  by  a  steel  member,  represents  the  strength  of 
support  for  deck  and  apron  in  the  same  degree  as  if  it  were  solid.  This 
statement  needs  no  more  argument  than  the  fact  that  a  wall  containing 
a  door,  properly  framed,  will  support  the  same  weight  safely  as  it  would 
if  it  were  solid. 

No.  2  shows  a  vaulted  chamber  arranged  longitudinally  in  the  interior 
of  the  spillway,  its  floor  of  concrete-steel  arches  resting  upon  transverse 
walls,  really  the  bottom  sections  of  the  partition  widened  in  section,  and 
its  walls  and  ceiling  being  formed  by  one  continuous  dome-like  structure, 
generally  of  hollow  brick  tile,  or  of  ferro-inclave.  A  considerable  space 
is  left  between  this  chamber  and  the  shell  of  the  spillway  structure, 
allowing  of  free  circulation  of  air  currents  around  it.  The  length  of  this 
interior  chamber  depends  upon  the  number  of  power  units,  generally 
one  unit  can  be  installed  between  two  spillway  partitions.  The  power 
chamber  or  operating  room,  or  by  whatever  name  it  becomes  known,  is 
continuous  and  need  not  be  subdivided  for  purposes  of  design  of  con- 
struction, though  it  may  be  desirable  to  partition  off  a  repair  shop  and 
perhaps  an  office  room.  This  vaulted  room  may  be  compared  with  the 
superstructure  of  the  general  power-house  design,  while  its  supports  are 
identical  with  the  ordinary  substructure  containing  the  pits  and  turbine 
bays.  All  of  this  is  readily  recognized  from  the  sections  shown,  and,  as 
a  matter  of  fact,  the  structural  arrangements  are  subject  to  such  a 
variety  of  designing  as  may  be  suggested  by  different  conditions  and 
requirements. 

No.  5  shows  the  feed-pipe  intake  passing  through  the  spillway  deck; 
it  may  be  as  shown,  or  higher  up;  the  feed  pipe  may  lead  in  straight  or 
with  a  quarter  turn, — all  matters  of  detail  for  particular  cases;  at  any 


270  HYDRO-ELECTRIC   PRACTICE 

rate,  the  water  is  drawn  from  the  upstream  side  of  the  spillway,  led  into 
the  turbine  case,  which,  as  here  shown,  is  that  of  a  vertical  shaft  wheel; 
it  may  be  of  the  horizontal  type,  in  fact  of  any  of  the  installations  which 
will  appear  further  on  as  part  of  the  discussion  of  hydraulic  equipment, 
all  depending  upon  the  required  output  and  available  space.  In  a  plant 
recently  designed  the  installation  consisted  of  a  line  of  two  54-inch 
turbines  on  one  horizontal  shaft  driving  one  generator. 

No.  6  is  the  supply  pipe,  and  at 

No.  7  is  shown  a  valve  gate  by  which  the  flow  in  the  pipe  is  fully 
controlled;  this  is  also  a  subject  of  detail,  offering  no  difficulty  of  solution. 

No.  8  is  the  turbine  case,  already  discusseo!. 

No.  9  shows  the  draft  tube  passing  into  the  pit.  Note  the  depression 
in  the  pit  excavation  below  the  draft  tube,  also  the  depression  of  the 
outflowing  water  surface  at  No.  4;  this  will  actually  exist  whenever 
water  is  passing  over  the  spillway,  excepting  during  storm  flow,  repre- 
senting the  siphon  action  of  the  water  as  it  passes  the  downstream  open- 
ing of  the  pit,  where  its  energy  is  that  due  to  its  mass  and  the  fall.  If 
the  overfall  on  spillway  crest  is  six  inches  deep,  the  volume  per  linear 
foot  of  spillway  is  approximately  1.2  cubic  foot  per  second,  which  with 
a  fall  of  42  feet,  that  of  the  section  shown,  represents  a  theoretical  energy 
at  the  toe  of  the  spillway  of  about  3000  ft.  pds.,  where  it  meets  the  tail 
water  passing  out,  and,  instead  of  exerting  its  force  on  the  river  bed 
material  or  the  spillway  apron,  it  is  turned  into  the  harmless  but  extremely 
useful  work  of  accelerating  the  motion  of  the  tail  water,  thereby  lowering 
it  below  the  draft  tube  and  incidentally  increasing  the  effective  working 
head  on  the  turbine.  The  conditions  which  give  rise  to  this  phenomenon 
would  usually  combine  to  cut  down  the  effective  head  of  the  plant  by 
raising  the  lower  level  in  the  tail-race  or  pit.  This  is  not  only  based 
upon  theory,  which  is  sound  enough,  but  has  been  actually  observed, 
and  the  author  hopes  to  find  opportunities,  before  very  long,  to  make 
tests  and  measurements  of  the  actual  work  of  the  overfalling  water 
expended  on  the  escaping  tail  water. 

No.  15  shows  two  waste  flumes  arranged  close  to  the  supply-pipe 
intakes,  by  which  the  accumulation  of  sediment  near  these  intakes  can 
be  avoided.  As  already  stated,  there  is  no  objection  to  the  arrangement 
of  the  supply-pipe  intake  at  a  higher  level.  The  intake  entrance  is  pro- 
tected by  a  trash  rack  operated  from  a  platform  on  the  spillway  crest. 
Raking  may  also  be  arranged  from  the  interior  of  the  spillway. 


STRUCTURAL   TYPES 


271 


POWER  SPILLWAY. 


FIG.  91 

H.E.EI66 

H.v.S. 


272  HYDRO-ELECTRIC    PRACTICE 

No.  14  shows  the  entrance  to  the  submerged  station,  which  is  from 
the  downstream  side  of  the  spillway  through  the  abutment,  entirely 
safe  and  as  convenient  as  any  transportation  arrangement  can  make  it; 
a  railroad  track  may  be  brought  to  this  entrance  or  carried  into  the 
station,  a  trainload  of  equipment  may  be  taken  into  the  station,— 
simply  a  question  of  available  space. 

No.  12  shows  the  end  door  and  entrance  into  the  operating  room. 

No.  13,  the  windows,  in  this  case  of  ordinary  rectangular  dimen- 
sions, because  the  apron  is  of  the  partial  type;  were  it  full,  the  light 
would  be  supplied  through  ship  lights;  there  need  be  no  scarcity  of 
light,  daylight  and  artificial;  when  water  overflows  the  spillway  the 
refracted  light,  through  the  water,  is  plentiful  and  most  beautiful. 

Abundance  of  circulating  air  is  secured  in  this  chamber;  if  anything, 
too  much  of  it  when  overflow  sucks  air  through  the  vents  under  the  crown 
from  the  interior  of  the  spillway,  thus  creating  a  considerable  air  current. 

The  equipment  as  herein  shown  in  No.  10  consists  of  a  vertical  or 
umbrella  generator,  an  exceedingly  economical  machine  both  as  regards 
material  and  dimensions,  and  of  high  efficiency;  witness  the  equipment 
of  the  Niagara  Falls  plant  and  many  of  the  most  recent  and  complete 
of  the  European  installations.  The  generator  may  be  of  the  ordinary 
type  coupled  to  the  shaft  of  a  horizontal  turbine,  or  a  pair;  the  vertical 
is  somewhat  more  economical  in  space.  There  is  plenty  of  room  for  the 
hydraulic  governor,  the  exciter  and  switchboards,  and  the  cable  galler- 
ies which  lead  out  to  the  abutments  and  thence  to  the  transformer  house 
or  transmission  line. 

No.  3  shows  the  space  available  for  the  handling  of  the  turbines  in 
placing  or  removing  them;  they  are  passed  through  the  floor  and  the 
draft  tubes  similarly  through  wells  arranged  in  the  lower  floor. 

No.  17  is  the  abutment  which  is  designed  to  protect  the  entrance 
leading  into  the  station  on  the  other  side  of  it  against  any  of  the  over- 
falling  water. 

The  advantages  represented  by  the  submerged  power  house  may 
be  enumerated  as  follows: 

First,  it  secures  the  highest  obtainable  hydraulic  efficiency  of  the 
available  flow  and  fall,  certainly  exceeding  that  of  any  other  arrange- 
ment, unless  it  be  in  a  power  house  at  the  end  of  the  spillway. 

Second,  it  represents  the  greatest  obtainable  economy  in  power-house 
construction,  and  in  this  respect  admits  of  no  rival  and  no  exceptions. 


OF  THE 

UNIVERSITY 


iiEEii 


View    25 


Submerged 


View    26 


House.  S» 


. 


UNIVERSITY  ] 

OF  J 


STRUCTURAL   TYPES  273 

Even  the  power  house  at  the  end  of  the  spillway  requires  a  separate 
structure,  unless  the  spillway  proper  is  shortened  for  that  purpose,  when 
it  represents  a  far  more  expensive  arrangement  than  a  separate  power 
house,  because  the  storm  overflow  will  be  much  higher  and  flood  more 
land,  etc.  The  saving  represented  by  the  submerged  power  house  should 
be  considerable  in  any  case  as  compared  with  the  separate  power  house, 
but,  even  if  the  cost  were  the  same,  the  advantages  secured  under  the 
first  item  represent  a  substantial  value. 

Third,  the  submerged  power  house  is  absolutely  safe  from  lightning 
danger;  it  cannot  be  struck,  nor  damaged  by  fire  in  any  manner. 

Fourth,  the  power  installation  may  be  of  gradual  growth  without 
the  necessity  of  erecting  an  unnecessarily  large  building  at  the  first. 
This  is  frequently  a  very  pertinent  point,  that,  while  the  spillway  must 
be  completely  built,  the  power  house  might  be  economized  on  until  the 
market  calls  for  the  output;  but  the  separate  power  house  must,  as  a 
rule,  be  as  completely  constructed  at  the  beginning  as  the  spillway  and 
dam,  even  though  at  first  only  a  part  of  the  power  installation  is  to  be 
placed.  In  the  submerged  power-house  type,  the  power  house  is  practi- 
cally constructed  when  the  spillway  is  in  commission,  the  interior  detail 
arrangement  can  be  made  just  as  conveniently  and  economically  at  any 
time  thereafter,  perhaps  with  considerable  saving  when  electric  power  is 
later  on  available  from  one  or  more  units. 

Fifth,  the  submerged  power  house  can  be  constructed — or,  more 
appropriately  speaking,  arranged — irrespective  of  the  condition  of  the 
river  or  the  season  of  the  year,  which  very  frequently  is  an  important 
matter  when  the  completion  of  the  plant  has  to  go  over  a  season  because 
of  high  water  or  serious  cold.  It  will  be  simply  interior  finishing. 

At  the  time  this  publication  goes  to  press,  the  first  of  this  type  of 
submerged  power  stations  has  been  completed'  and  is  in  operation.  It 
is  located  on  the  Patapsco  River  some  15  miles  from  Baltimore,  Md., 
and  is  easily  reached  from  that  city  by  the  B.  &  O.  R.  R.  going  to 
Illchester,  Md.,  or  by  the  electric  Interurban  to  Ellicott  City,  Md.,  the 
plant  being  only  a  short  distance  from  either  point. 

The  development  is  the  project  of  the  Patapsco  Electric  and  Manu- 
facturing Company,  of  which  Mr.  Victor  G.  Bloede,  of  Baltimore,  is  the 
President  and  Mr.  Otto  Wunder,  of  Ellicott  City,  Md.,  the  Superintendent. 
The  Patapsco  River  is  one  of  the  oldest  water-power  streams  in  this 
country,  and  one  of  the  earliest  developments  at  Ellicott  City,  consisting 

18 


274  HYDRO-ELECTRIC   PRACTICE 

of  a  spillway  and  diversion  canal  and  constructed  in  the  last  century, 
is  still  in  commission  operating  some  large  flour  mills  located  at  Ellicott 
City,  and  it  seems  peculiarly  fitting  that  the  latest  development  of  hydro- 
electric plant  types  should  find  its  cradle  on  this  stream  which  is  so  full 
of  water-power  history. 

The  Patapsco  Electric  and  Manufacturing  Company  now  operate 
two  hydro-electric  plants  on  the  Patapsco  River,  the  one  here  referred 
to  with  the  submerged  power  station,  and  an  older  plant  some  two  miles 
above  this  on  the  same  stream.  Mr.  Otto  Wunder  has  charge  of  both  of 
these  plants,  and  is  therefore  well  qualified  from  the  view-point  of  the 
practical  station  operator,  the  man  who  finds  or  misses  the  faults  and 
merits  more  readily  than  the  designer  and  constructor,  to  draw .  com- 
parisons between  the  usual  type  of  the  separate  power  house  with  this 
submerged  station  located  in  the  interior  of  the  spillway,  and  Mr.  Wunder 
is  a  man  whose  talk  is  plain  and  convincing  because  he  knows  what  he 
is  talking  about. 

Views  21  to  32  are  of  the  Patapsco  plant. 

View  21  shows  the  construction  of  the  spillway,  which  was  executed 
by  the  Ambursen  Hydraulic  Construction  Company,  of  Boston,  Mass., 
who  make  a  specialty  of  this  type  of  spillways  and  to  whom  the  author 
is  indebted  for  these  construction  views.  In  No.  21  the  spillway  par- 
titions are  being  formed  and  the  openings  for  the  interior  chamber  are 
plainly  visible. 

No.  22  is  an  end  view,  showing  the  rock  bank  against  which  the 
abutment  is  placed  and  through  which  entrance  is  gained  into  the  interior 
station. 

No.  23  is  a  longitudinal  view  of  the  interior,  giving  a  good  idea  of 
its  dimensions;  the  floor  of  the  station  room  is  being  placed. 

No.  24  shows  the  placing  of  one  of  the  turbine  supply-pipe  collars 
in  the  upstream  face,  the  deck,  of  the  spillway;  it  also  reveals  the  waste 
flume,  an  underflow  sluice,  in  the  lower  left-hand  corner,  by  which  part 
of  the  stream's  flow  is  controlled  during  construction. 

No.  25  is  an  upstream  view  of  the  completed  spillway  with  the 
supply-pipe  openings,  which  are  covered  with  trash  racks  and  gates. 

No.  26  is  a  downstream  view,  showing  the  partial  overfall  apron 
and  the  openings  in  which  the  windows  of  the  station  are  placed. 

No.  27  contains  a  downstream  view  of  the  completed  structure, 
showing  the  water  passing  through  the  underflow  sluice;  the  windows 


Submerged 
Power  House 


Submerged 
Power  Hous 


Submerged 
Power  House 


STRUCTURAL   TYPES  275 

of  the  power  station  are   plainly  visible  here;   they  are  of   ample  size, 
making  the  interior  station  as  bright  as  day. 

No.  28  is  of  the  interior,  with  two  of  the  power  units  installed  and 
operating;  the  double  horizontal  reaction  turbines  are  in  cases;  the 
supply  pipe  enters  the  case  at  the  top. 

No.  29  is  a  similar  view  taken  from  the  other  end,  and 

No.  30  shows  the  two  revolving  field  alternators  and  the  exciters. 

Views  31  and  32  are  of  the  spillway  with  water  flowing  over  its 
crest,  this  plant  having  already  passed  through  two  of  the  highest  of 
the  known  flood  rises  on  that  stream.  Under  this  condition  the  over- 
fall is  carried  safely  down  the  apron,  the  light  shines  through  it,  and  the 
appearance  of  this  spectacle  from  the  interior  chamber  is  not  readily 
forgotten.  The  station  is  absolutely  safe  from  leakage  or  any  moisture 
whatever. 

At  the  present  time,  November,  1907,  two  other  plants  of  the  sub- 
merged power  station  are  being  constructed,  one  at  Delta,  Pa.,  and  the 
other  on  the  Big  Horn  in  Wyoming;  these  are  both  60  feet  high  and  will 
develop  about  1500  kilowatts  output.  Arrangements  are  also  about 
made  for  the  construction  in  Canada  of  a  similar  plant,  in  which  the 
dam  will  be  800  feet  long  and  45  feet  high,  the  submerged  station  to 
contain  probably  twenty  turbine  units,  to  which  will  be  coupled  pulp 
grinders.  This  spillway  will  practically  contain  a  mechanical  pulp-mill, 
all  the  operations  of  preparing  the  pulp  wood,  grinding  the  same  by 
direct  connected  pulp  grinders,  running  the  pulp  through  wet  machines, 
and  manufacturing  it  into  pulp  sheets  ready  for  shipment,  will  be  carried 
on  in  the  interior  of  this  spillway;  and  the  cars  will  be  switched  and 
loaded  in  the  submerged  station,  while  it  is  likewise  seriously  intended 
to  provide  living  quarters  for  the  operatives  in  it,  as  the  location  is 
remote  from  any  present  settlement.  All  this  is  entirely  feasible,  and 
the  realization  of  such  a  plan  represents  a  very  large  saving  as  com- 
pared with  the  erection  of  a  separate  pulp-mill  outside  of  the  spillway, 
diverting  the  flow  to  a  separate  power  house,  and  erecting  lodging- 
houses,  etc. 

Pumping  plants  for  water  supply  can  be  conveniently  thus  placed 
in  the  interior  of  the  .dam  which  creates  the  reservoir,  and  electro-chemical 
plants  could  be  likewise  thus  arranged  with  a  considerable  saving  in  cost. 


CHAPTER   IX 

EQUIPMENT 

WHILE  it  is  the  purpose  of  the  structures  described  in  the  pre- 
vious chapter  to  collect  and  make  available  the  natural  forces  for  their 
ultimate  utilization,  the  realization  of  it  all  is  left  to  the  agents  by 
which  the  energy  of  falling  water  is  made  to  do  the  work  and  light  the 
way  of  man  many  miles  away.  The  virgin  power  is  hydraulic,  which 
by  hydraulic  turbines  is  converted  into  mechanical  energy,  the  latter 
by  electric  generators  is  changed  into  electric  current,  which  is  finally 
transmitted  to  the  market;  the  equipment,  therefore,  is  that  represent- 
ing these  three  stages  of  conversion,  and  will  be  treated  in  this 
chapter  as  that  required  for  hydraulic,  mechanical,  electric,  and  trans- 
mission duties. 

The  presentation  of  this  subject  of  equipment  will  be  found  analogous 
to  that  of  the  former  topics, — that  is,  with  and  for  the  purpose  of  pre- 
senting the  practical  features,  only  so  much  of  the  fundamental  theories 
being  developed  as  seems  essential  to  a  clear  understanding  of  the  results 
to  be  sought  by  the  employment  of  this  equipment.  Designing  and 
construction  of  equipment  are  necessarily  confined  to  the  general  outlines 
of  modern  types,  and  the  same  is  true  of  the  output.  As  a  proper  treat- 
ment of  the  different  makes  of  equipment,  even  if  confined  to  American 
usage,  is  beyond  the  desired  scope  of  this  work,  reference  to  any  specific 
type  has  been  avoided;  when  this  rule  is  apparently  set  aside,  it  is  in 
the  case  of  a  special  and  patented  device. 

ARTICLE  79.  Hydraulic  Equipment,  Theory.  -  -  Water-power  is  ren- 
dered serviceable  as  mechanical  energy  through  the  agency  of  hydraulic 
turbines.  The  energies  of  water  are  of  position,  potential,  and  of  motion, 
kinetic;  the  first  is  expressed  by  gravity  through  the  weight  of  the  mass 
acting  under  pressure  due  to  fall;  the  second  by  impact  due  to  the 
velocity  of  flow;  -the  sum  of  the  two  forms  hydro-dynamic  energy. 

Dynamic  energy  is  produced  whenever  the  direction  or  the  velocity 
of  a  flowing  stream  or  jet  is  altered;  it  may  find  expression  as  impulse, 
which  is  pressure  forward  in  the  direction  of  the  flow,  or  as  reaction,  the 
pressure  backward  in  a  direction  opposite  to  that  of  the  flow,  both  forces 

276 


EQUIPMENT  277 

being  those  existing  in  all  bodies  under  stress,  action  and  reaction,  which 
when  not  restrained  are  equal  in  intensity. 

The  potential  energy  is  expressed  by  the  product  of  the  weight  of 
the  mass  and  the  height  of  its  fall;  this  may  be  utilized  to  do  work;  one 
cubic  foot  of  water  falling  ten  feet  represents  625  foot  pounds,  and  in 
this  form  water-power  energy  was  employed  during  the  earlier  periods 
of  our  civilization  by  letting  water  fall  into  the  buckets  of  the  overshot 
and  breast  or  middleshot  wheels,  which  rotated  around  a  horizontal 
axis,  from  which  the  resultant  power  was  taken  by  gear  connections  to 
mechanical  drives;  about  fifty  per  cent,  of  the  initial  energy  was  thus 
realized  for  useful  work. 

The  kinetic  energy  is  that  of  impact  due  to  the  velocity  of  flow; 
it  may  be  converted  into  useful  work  by  the  aid  of  undershot,  paddle, 
and  current  water-wheels,  in  which  the  flowing  water  strikes  the  vanes 
secured  to  the  hub  of  a  wheel;  not  to  exceed  45  per  cent,  of  the  original 
energy  may  be  realized. 

The  sum  of  potential  and  kinetic  energies  represents  the  hydro-dynamic 
equation;  the  first  is  the  pressure,  the  second  the  velocity;  combined 
they  represent  the  material  energy  created  by  water-power.  While  a 
stream  passes  as  a  continuous  volume  through  confined  channels,  its 
dynamic  energy  remains  intact;  if  the  velocity  increases,  the  pressure  is 
diminished,  and  vice  versa,  the  aggregate  remains  the  same  and  available 
to  perform  work;  if  its  free  flow  is  altered  in  direction,  without  shock, 
the  total  energy  passes  into  the  new  direction;  but  shock  is  overcome  by 
impact,  which  is  work  done,  entailing  the  expenditure  of  some  of  .the 
available  energy.  If  the  obstruction  to  its  free  passage  is  of  a  movable 
device,  energy,  expressed  as  impulse  or  reaction  or  both,  may,  in  over- 
coming the  obstacle  to  its  free  flow,  be  transferred  to  the  movable  device, 
which  takes  up  this  energy,  or  so  much  of  it  as  is  not  required  to  over- 
come mechanical  resistances.  This  is  the  principle  of  the  turbine;  the 
direction  of  a  stream  is  altered  by  interposing  movable  vanes,  and  the 
force  of  the  stream  which  would  resist  such  a  change  REACTS  upon:,  the 
vanes  and  through  their  motion  is  converted  into  mechanical  work.  . 

Dynamic  energy  finds  its  final  expression  in  weight;  the  absolute 
unit  is  1  -T--  32.16,  being  the  force  which  will  move  one  pound  one  foot  in 
one  second.  Energy  of  water  is  its  mass,  the  product  of  its  weight  and 
the  absolute  force  unit.  When  water  moves  inertia  is  overcome  and 
motion  is  created  and  maintained  by  the  acceleration  of  gravity  in 


278  HYDRO-ELECTRIC    PRACTICE 

response  to  a  certain  fall  and  flow,  expressed  in  feet  per  second.  The 
momentum  of  the  moving  water  is  the  product  of  its  mass  and  the  velocity 
with  which  it  flows. 

F  represents  the  theoretical  force  of  the  momentum  of  flowing  water; 
W  represents  its  mass; 

w  represents  the  weight  of  one  cubic  foot  of  water  (=  62.5  Ibs.)  ; 
g  represents  acceleration  of  gravity  (=  32.16)  ; 
V  represents  velocity  of  flow  in  feet  per  second; 
h  represents  fall  in  feet;  and 

A  represents  the  cross-sectional  area  of  the  flowing  stream  or  jet  in 
cubic  feet; 

F  =  mass  X  velocity 


Static  pressure,  P  =  wAh,  and  with  V  expressed  in  h,  dynamic 
force  F  =  2  w  A  h  or  double  that  of  static  pressure. 

In  the  following  discussion  dynamic  force  will  be  expressed  by 

F  =  ^V. 

g 

A  stream  enters  a  plane,  Fig.  92,  A  C,  at  A,  without  shock  or 
change  of  flow  section;  its  entry  is  in  the  direction  of  A  B,  but  it  is  forced 
continuously  away  from  this  into  a  new  direction,  A  C.  At  the  point 
of  entry  the  stream  has  no  tendency  to  deflect,  and  it  therefore  requires 
some  retarding  force  to  cause  this  deflection,  which  in  turn  sets  up  an 
accelerating  force  in  the  stream  acting  continually  in  a  direction  at 
right  angles  to  its  original  motion.  At  C,  or  at  any  other  point  along  the 
plane  A  C,  the  deflection  C  B  =  A  C  sin  e,  and  the  force  which  has  caused 
it  is  represented  by  the  product  of  C  B,  as  the  measure  of  velocity  divided 
by  the  period  of  time,  or  AC  sin  e  -v-  t,  and  the  pressure  of  the  mass  of 
water  passing  over  AC  per  .second. 

If  the  plane  AC,  Fig.  93,  is  not  fixed,  theoretically  the  accelerating 
force  AC  sin  e  will  act  upon  the  plane  in  direction  CB,  and  AC  will  occupy 
the  position  DB  when  the  stream  arrives  at  C,  and  if  another  stream 
then  enters  at  D,  and  so  on,  the  plane  will  continue  to  move  in  the  direc- 
tion BE.  Impact  wheels  representing  the  earliest  turbine  tyjjes  were 


EQUIPMENT  279 

designed  on  this  principle,  from  16  to  20  rectangular  blades  or  paddles 
being  fastened  to  a  wheel  at  inclinations  of  50°  to  60°,  the  water  striking 
the  paddles  at  about  a  right  angle. 

AC,  Fig.  94,  is  a  curved  vane ;  the  stream  enters  at  A  without  shock 
and  leaves  it  at  C;  the  force  F  in  the  stream's  original  direction  equals 
the  impulse  less  the  reaction,  or 

F  =  I  —  R'  (the  component  of  R), 
R'  =  R  cos  x,  and,  as 

I-R-*V, 

g 
w 

F  =  "v  V  (1  — cosx). 
g 

In  Fig.  95  the  same  conditions  prevail  as  in  the  previous  example, 
excepting  that  the  angle  at  the  exit  exceeds  90°  and 

F  =  I  +  R', 
R'  =  R  cos  180  —  x, 
=  R  cos  x, 

and,  as  in  the  previous  case, 

F  =  -  V  (1— cosx). 

This  principle  was  utilized  in  the  impact  wheels  with  curved  vanes,  also 
called  tub  wheels,  or  the  French  roues  en  curves,  and  the  German 
Kuferraeder,  of  which  class  the  Burdin  turbine  realized  probably  the 
highest  efficiency. 

In  Fig.  96  the  vane  is  bent  completely  back,  so  that  the  direction  of 
the  exit  flow  parallels  that  of  the  entry  and 

W 
F  =  I  +  R  =  2  —  V, 

g 

or  double  that  of  the  normal  value  of  F.  It  must  be  noted  that  F  repre- 
sents the  force  in  the  direction  of  the  flow  of  entry  and  that  the  vanes 
considered  have  been  fixed. 


280  HYDRO-ELECTRIC   PRACTICE 

In  Fig.  97  the  vane  has  its  individual  motion  U,  and  the  velocity 
of  the  stream  along  the  surface  of  the  vane  and  relative  to  it  becomes 
V  —  U,  while  the  force  of  the  stream  in  the  direction  of  its  flow  is  as  before 
excepting  as  to  the  value  of  the  velocity,  or 

W 

F  =  ™  (1  —  cosx)  (V--TJ). 

o 

Fig.  98  is  an  analysis  of  the  theory  of  the  entry  and  exit  of  the  water 
in  contact  with  a  moving  surface. 

V  is  the  relative  entry  velocity; 

e  is  the  entry  angle  between  tangent  to  point  of  entry  and  nor- 
mal to  direction  of  the  vane  motion; 

V  is  the  absolute  velocity  of  entry,  and 

e'  the  angle  of  its  direction  with  that  of  the  vane's  motion  normal; 

U  is  the  velocity  of  the  vane; 

V  —  U,  effective  velocity  of  the  water  along  the  surface  of  the  vane ; 

V,  the  relative  exit  velocity; 

X,  the  exit  angle  of  tangent  to  point  of  exit  and  normal  to  motion 
direction  of  the  vane; 

V",  the  absolute  exit  velocity. 

Fig.  99  completes  the  consideration  of  the  characteristics  of  flow 
along  moving  vanes  (not  rotary),  exemplifying  the  determination  of 
the  total  force  acting  in  the  direction  of  the  motion  of  the  vane,  from  the 
components  of  impulse  and  reaction. 

D  marks  the  direction  of  the  flow  and 

U  marks  the  direction  of  the  vane's  motion; 

e  is  the  angle  formed  by  these  two; 

W 

the  available  force  is  F  =  —  V, 

g 

W 

the  impulse  component  -»--(¥  cos  e), 

o 

the  reaction  component  =  -  -  (V  cos  x') , 

and  F  =  —  (V  cos  e  -  V,  cos  x'). 
g 


EQUIPMENT 


281 


B 

H.E.P.168 
H.V.S. 


Fig.  94 


H.E.P.170 
H.v.S. 


H.E.P.171 
H.v.S. 


Fig.  95 


F 


R- 


Fig.  96 


H.E.P.172 
H.v.S. 


282  HYDRO-ELECTRIC   PRACTICE 

The  theoretic  work  of  the  moving  vane  equals  the  product  of  the  force 
exerted  against  its  surface  and  the  space  traversed  by  the  moving  vane 
during  a  unit  period  of  time,  or,  from  Example  Fig.  97, 

k  =  F  U  =  —  (1  --  cos  x)  (V  —  U)  U. 

O 

These  deductions  of  the  elementary  characteristics  of  the  force, 
velocities,  and  directions  have  been  of  surfaces  moving  in  rectilinear 
directions,  and,  while  not  reflecting  the  exact  conditions  of  the  turbine, 
they  gradually  lead  up  to  the  practical  utilization  of  these  general  prin- 
ciples by  turbines  in  which  the  motion  of  the  vane  is  rotary  about  a  fixed 
point. 

In  Fig.  100  AC  is  a  curved  vane  rotating  around  the  fixed  axis  X; 
the  stream  enters  at  A; 

r  is  the  radius  of  rotation  of  the  point  of  entry  A; 

U  is  the  velocity  of  rotation  or  of  revolution,  its  direction  being 

normal  to  r; 

V  is  the  relative  entry  velocity; 
A  V  V  U  is  the  entry  parallelogram; 
e,  the  angle  formed  by  directions  of  flow  and  vane  motion; 
V,  the  absolute  velocity  of  the  stream. 

The  water  leaves  the  vane  at  C;  r'  is  the  radius  of  this  point; 

U'  is  the  velocity  of  the  vane  at  C,  normal  to  r'; 
V,  the  relative  exit  velocity  of  the  water. 

Completing  the  exit  parallelogram  C  V,  V",  U', 

x  is  the  angle  between  relative  exit  velocity  and  direction  of  the 

vane  motion  reversed; 
V",  the  absolute  exit  velocity; 
U',  the  vane  velocity;  and 
x',  the  angle  between  absolute  exit  velocity  and  vane  motion. 

Heretofore,  when  the  motion  of  the  vanes  was  considered  to  be 
in  rectilinear  directions,  the  relative  velocities  of  entry  and  exit  water 


EQUIPMENT 


283 


Fig.  97 


H.E.P.173 
H.V.S. 


Entry 


H.E.P.174 
H.V.S. 


Fig.  98 


Exit 


Fig.  99 


H.E.P.175 
H.V.S. 


284  HYDRO-ELECTRIC    PRACTICE 

were  assumed  to  be  equal,  because,  presumably,  the  vane's  motion  was 
equal  at  both  ends;  in  the  case  now  discussed,  where  the  vane's  motion 
is  a  rotary  one  equal,  say,  to  n  revolutions  per  minute, 

U  =  2r7tn   and  U'  =  2r/7tn  or    ~  =  r  . 

IT'      r 

The  impulse  and  reaction  forces  exerted  on  the  vane,  as  due  to  the 
absolute  entry  and  exit  of  the  water  on  and  off  the  vane,  or  from 

F  =  —V  and  —  V",  are 
g  g 

W 

for  the  impulse  I  =  -  -V  cos  e   and 

g 

W 

reaction  R  =  — V"  cos  x', 

and  the  work  produced  on  the  vane  or  k  =  impulse  —  reaction, 

k  =  ^  (UV'cose  -  U'V'cosx'). 

In  Fig.  101  the  vane  has  a  rotary  motion  as  in  the  last  example,  but 
the  stream  enters  the  vane  at  the  extremity  of  its  peripheral  path  and 
finds  its  exit  nearer  the  axis,  while  these  conditions  of  entry  and  exit 
were  reversed  in  the  previous  example.  These  two  represent  inward 
and  outward  flow  conditions  as  relating  to  the  locus  of  the  fixed  axis 
around  which  the  vane  revolves;  all  the  theories  of  one  apply  likewise 
to  the  other. 

This  completes  the  theory  of  hydraulic  turbines  as  based  upon  the 
flow  of  water  along  the  surfaces  of  moving  vanes ;  as  a  matter  of  fact,  the 
actual  flow  through  the  majority  of  turbines  takes  place  in  pipes  rather 
than  along  surfaces,  which,  however,  makes  no  difference  in  the  .theories 
expounded  excepting  that  the  static  pressures  are  added  and  that  the 
law  of  continuity  of  flow  governs  the  water's  progress  while  passing 
through  the  turbine. 

Summarizing  these  theoretical  fundamentals,  it  is  found  that  the 
work  of  a  turbine  is  caused  by  the  dynamic  energy  of  the  water  expressed 
by  the  product  of  its  mass  and  motion  acting  through  impulse  and 


EQUIPMENT 


285 


reaction  upon  curved  vanes  of  free  rotary  motion;  that  the  degree  of 
work  thus  imparted  to  the  vane,  or  the  wheel  consisting  of  a  system  of 
such  vanes,  depends  chiefly  upon  the  relative  values  of  the  components  of 
impulse  and  reaction  force,  which  are  influenced,  if  not  entirely  determined, 
by  the  designs  of  the  vane  or  bucket,  at  the  entry  and  exit  points,  whereby 
the  velocities  and  directions  of  entry  and  exit  flow  are  largely  fixed;  the 


Fig.  100 


H.E.P.176 
H.v.S. 


Fig.  101 


H.E.P.177 
H.V.S. 


motion  of  the  wheel  or  bucket  becomes  a  factor  in  the  work  expression, 
while  the  shape  of  the  vane  between  entry  and  exit  is  of  lesser  influence. 

It  is  evident  that  turbine  designs  should  aim  at  the  ideal, — namely,  the 
greatest  velocity  of  the  moving  vane  with  the  highest  value  of  work, — and  how 
this  may  be  secured  theoretically,  and  how  far  it  is  likely  to  be  realized 
practically,  under  fixed  conditions,  will  appear  further  on  in  this  chapter. 

ARTICLE  80.  Classifications  of  Turbines.  —  Any  mechanical  device 
which  whirls  about  a  fixed  point  may  be  called  a  turbine.  Applied  to 


286 


HYDRO-ELECTRIC    PRACTICE 


hydraulic  motors  a  turbine  is  a  wheel  which  turns  around  a  fixed  shaft 
under  the  influence  of  flowing  water  by  the  force  of  impulse,  pressure,, 
and  reaction,  or  a  combination  of  these.  Hydraulic  motors  are  classified 
as  water-wheels  and  turbines,  which  is  descriptive  of  the  older  and  modern 
types,  the  former  comprising  those  which  utilized  the  potential  or  the 
kinetic  energy,  while  the  turbine  class  includes  all  motors  in  which  both 
of  these  forces  unite  in  the  production  of  the  useful  work.  The  water- 
wheel,  in  the  above  sense,  need  not  be  considered  in  connection  with 
modern  hydro-electric  practice,  as  it  is  represented  by  the  overshot, 
breast,  and  undershot  wheels  of  the  older  mill  practice  which  have  been 
superseded  by  the  modern  turbine. 

The  primary  classification  of  turbines  is  based  upon  the  action  of 
the  water,  which  may  be  impulse,  pressure,  and  reaction,  but  never 
weight  only.  It  is  by  impulse  when  the  water  strikes  buckets  or  vanes, 
more  or  less  perpendicularly  and  spreads  out  over  the  surfaces  in  all 
directions;  by  pressure  when  the  water  glides  along  the  curved  surfaces, 
of  vanes  in  one  fixed  direction,  only  partially  filling  the  passages;  and 
it  is  by  reaction  when  water  passes  through  closed  passages  formed  by 
curved  vanes  in  one  fixed  direction  and  completely  fills  these  passages. 

Turbines  acting  under  pressure  partake  some  of  the  impulse  and  some 
of  the  reaction  characteristics,  and  therefore  the  classification  with  regard 
to  the  action  of  the  water  may  be  limited  to  impulse  and  reaction  tur-. 
bines,  though  even  this  is  not  absolutely  correct,  since  a  turbine  of  either 
class  may,  under  certain  conditions,  partake  of  some  of  the  character- 
istics of  the  other. 

The  theoretical  differences  between  the  impulse  and  the  reaction 
turbines  are  expressed  by  the  following  paralleled  conditions: 


IMPULSE. 

The  flow  is  under  atmospheric  pressure  through 

passages  only  partially  filled; 
The   velocity  differs  in  all  parts  of  the  turbine 

without  constancy  of  ratio; 

The    entry    and    exit    being    under    atmospheric 

pressure,  the  energy  at  entry  is  kinetic  only; 
The  flow  through  the  turbine  is  neither  accelerated 

nor  retarded; 
The  effective  head  is  that  from  upper  pool  level 

to  the  level  of  entry  point; 
The  effective  head  cannot  be  made  available  to 

the  level  of  the  lower  pool  by  means  of  draft 

tubes. 


REACTION. 

The  flow  is  free  from  atmospheric  pressure  through 

passages  completely  filled. 
The  flow  is  subject  to  the  law  of  continuity  with 

a  fixed  ratio  of  velocity  in  all  parts  of  the 

turbine. 
Entry  and  exit  are  under  water  and  entry  energy 

is  potential. 
The  flow  in  passage  is  accelerated  and  retarded. 

The  effective  head  is  that  from  the  upper  pool 
level  to  the  level  of  the  point  of  exit. 

The  head  can  be  made  available  to  the  level  of 
the  lower  pool  by  the  aid  of  draft  tubes  within, 
the  limit  of  the  atmospheric  column. 


EQUIPMENT  287 

The  second  important  classification  of  turbines  is  based  upon  the 
direction  of  the  entering  and  passing  water  as  inward,  outward,  down- 
ward, or  upward,  or  expressed  in  relation  to  the  shaft  as  radial  or  axial 
or  parallel,  and  for  impulse  wheels  as  tangential  to  the  periphery  of  the 
wheel.  Impulse  turbines  are  therefore  also  called  tangential  turbines,, 
while  reaction  turbines  in  this  respect  are  defined  as 

Radial — outward  flow,  as  in  the  Fourneyron  type, 

Axial — downward  flow,  as  in  the  Jonval  type, 

Radial — inward  flow,  as  in  the  Francis  type, 

Mixed  flow,  as  represented  by  the  modern  American  turbines. 

A  third  turbine  classification  relates  to  the  character  of  the  control 
of  the  flow  into  the  turbine  by  means  of  guide-wheels  and  gates,  which 
are  of  cylinder,  register,  and  wicket  types,  the  details  of  which  are  ex- 
plained further  on;  and  the  fourth  and  final  classification  is  that  based 
upon  the  method  of  installation  as  being  on  a  vertical  or  a  horizontal 
shaft. 

Thus  a  turbine  is  properly  designated  as  a  vertical,  wicket-gate, 
mixed-flow  turbine,  or  a  horizontal,  cylinder-gate,  radial  inward  flow 
turbine,  or  a  tangential  (impulse)  turbine,  which  is  always  on  a  horizontal 
shaft. 

Additional  definitions  to  these  quoted  relate  to  manufacturer's 
special  designs  of  shape,  dimensions  and  spacing  of  buckets,  gate  devices, 
or  particular  structural  features,  or  denoting  the  names  of  the  originator 
of  the  type  or  of  the  maker. 

ARTICLE  81.  Description  of  the  Mixed -flow  Reaction  Turbine, — A 
reaction  turbine  consists  of  the  runner,  guide-wheel,  gates  and  rigging, 
and  the  case. 

Fig.  102  shows  a  typical  American  reaction  turbine  runner,  which, 
as  compared  with  those  used  abroad,  differs  chiefly  by  the  shape  and 
dimensions  of  the  buckets.  The  aim  is  to  secure  in  the  runner  the  largest 
possible  discharge  capacity  with  the  smallest  diameter  and  therefore 
the  least  quantity  of  metal,  to  utilize  the  largest  ratio  of  the  available 
reactionary  force,  and  to  obtain  the  highest  speed  of  rotation. 

The  velocity  of  the  runner,  under  a  given  head,  is  inversely  as  its 
diameter;  therefore,  to  increase  the  velocity  by  the  reduction  of  the 
diameter  would  defeat  the  other  equally  important  desideratum  of  a 
large  discharge  capacity;  this  latter  is  secured  in  the  American  type 
runner,  at  some  advantage  over  others,  by  the  shape  of  the  buckets  and 


288 


HYDRO-ELECTRIC    PRACTICE 


the  axial  depth  of  the  entry  passages.  These  entry  areas  are  made  as 
large  as  possible  not  by  an  increase  of  the  runner's  diameter,  but  by 
deepening  the  vertical  sections  of  the  vanes,  while  the  outflow  sections 


Fig.  103 


H.E.P.179 
H.  v.  S. 


Fig.  104 

Typical  Reaction 
Turbine  Runner 

-c: 


u — 


— S 


B 


B 


Axial  Section 


H.E.P.  180 
H.v.S. 


are  enlarged  by  the  broad  dishing  of  the  vanes.  In  this  manner  the 
runner  is  given,  as  compared  to  its  diameter,  an  abnormally  large  entry 
and  exit  area,  while  the  curvature  of  the  vanes  is  such  that  the  flow, 
entering  inward  radially,  passes  downward  axially  and  leaves  outward 


Fig.  105 


Upper 
radial  Section 


H.E.P.181 
H.V.S. 


Fig.  106 


Lower 
radial  Section 


.E.P.182 
H.V.S. 


radially,  and  therefore  its  exit  direction  is  nearly  reversed  from  that  of 
entry,  which,  as  has  been  shown  in  Article  79,  Fig.  96,  results  in  the 
utilization  of  the  greatest  amount  of  the  available  reaction  force. 

Fig.  103  shows  the  runner  in  the  upright  position;  E  is  the  entry 
section,  and  the  arrows  e  x  indicate  the  reversal  of  the  flow  direction 
between  entry  and  exit. 


Figf.  102 


H.E.P.178 
H.  v.  S. 


Reaction  Runner. 


Wicket-Gate  Guide- Wheel. 


EQUIPMENT 


289 


TT 


Fig.  108 

Guide  Vane 
H.E.P.184 
H.v.S. 


Fig.  104  shows  an  axial  section  of  the  runner  and  its  parts,  H  being 
the  hub,  C  being  the  crown,  R  being  the  rim,  B.  being  the  bucket. 

Fig.  105  is  a  radial  section  just  below  the  crown  plate,  showing  the 
shape  of  the  top  ends  of  the  vanes,  their  connection  to  the  hub,  and  the 
boring  left  for  the  shaft. 

Fig.  106  is  a  radial  section  near  the  bottom  of  the  runner  through 
the  rim  band  where  the  dishing  out  of  the  vanes  first  begins;  the  metal 
here  is  no  thicker  than  at  the  upper  section  shown  in  Fig.  105. 

Runners  are  usually  made  of  one  cast  with  the  hub;  only  a  few  of 
the  manufacturers  in  this  country  depart  from  this  practice  by  casting 

all  the  vanes  separately  and  then  set- 
ting them  in  the  mould  of  the  hub  cast 
and  thus  securing  their  fixed  position 
around  it. 

Guide-wheels  are  designed  to  suit  the 
different  gate  devices ;  they  generally  con- 
sist of  two  circular  plates  between  which 
the  guide-vanes  are  fixed  stationary  in 
positions  diagonal  to  the  axis  of  the 
wheel;  this  guide-wheel  slides  over  the 
crown-plate  and  rim  band  of  the  runner. 
Fig.  107  shows  a  guide-wheel  in 
which  the  guide-vanes  are  the  gates;  it 
represents  the  general  type  of  the  Amer- 
ican wicket  gate,  the  movable  shutters  or  gates  performing  also 
the  office  of  guiding  the  water  into  the  runner.  The  operation  of 
the  shutters  is  by  means  of  a  segmental  spur  gear,  G,  actuating  the 
gate  rods  R.  the  ends  of  which  are  firmly  secured  to  the  bottom  of 
the  gear  section. 

Fig.  108  shows  horizontal  and  vertical  sections  of  the  guide-vanes 
and  shutters,  the  upper  at  TT  being  taken  at  the  top  of  the  shutter  and 
BB  at  the  bottom,  while  EE  is  a  vertical  cross  section. 

The  guide-wheel  with  fixed  guide-vanes  is  employed  in  connection 
with  the  other  gate  devices;  cylinder  and  register  type;  the  former 
consists  of  a  cylinder  sliding  over  the  outside  or  inside  periphery  of  the 
guide-wheel  frame,  while  the  second,  as  its  name  implies,  resembles  a 
hot-air  register,  being  arranged  in  the  crown-plate  or  periphery  of  the 
guide-wheel. 


19 


290  HYDRO-ELECTRIC    PRACTICE 

Fig.  109  is  the  complete  plan  of  an  American,  mixed-flow,  wicket- 
gate  turbine,  in  which 

1  represents  the  runner  proper; 

2  represents  the  guide- vanes  and  gates; 

3  represents  the  guide  bolts  securing  the  gates  to  the  guide 

or  gate- wheel  frame; 

4  represents    the   column   bolts   which   connect    the    circular 

plates  of  the  guide  or  gate- wheel; 

5  represents  the  draft  tube  secured  to  the  bottom  plate  of 

the  gate-wheel; 

6  represents  the  lignum  vitae  packing  which  surrounds  the 

step  of  the  turbine  shaft; 

7  represents  the  spider  or  frame  in  which  the  turbine   shaft 

rests  or  is  stepped; 

8  represents  the  bottom  plate  of  the  gate-wheel; 

9  represents  the  top  plate  of  the  gate- wheel; 

10  represents  the  guide-pins; 

11  represents  the  gate-rods  by  which  the  gates  are  operated; 

12  represents  the  gate-operating  device; 

13  represents  the  spur-gear  sector  to  which  the  gate-rods  are 

secured ; 

14  represents  the  spur  pinion  which  is  operated  by  means  of  the 

shaft; 

15  represents  the  gate  shaft  which  is  in  practice  connected  to 

the  turbine  governor; 

16  represents  the  coupling  of   the  gate   shaft   to   its  upper  or 

lateral   connection,  as  the  turbine   may  be   placed  on  a 
vertical  or  horizontal  shaft; 

17  represents  the  turbine  or  wheel  shaft; 

18  represents  the  turbine  or  wheel  shaft  coupling; 

19  represents  the  rim  or  runner  band; 

20  represents  the  runner  bucket; 

21  represents  the  runner  hub. 

Fig.  110  shows  the  complete  plan  of  an  American,  mixed-flow, 
cylinder-gate  turbine,  in  which  the  following  are  the  detail  parts  and 
their  nomenclature: 

1  represents  the  runner; 

2  represents  the  runner  hub; 


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291 


292  HYDRO-ELECTRIC    PRACTICE 

3  represents  the  runner  rim  band; 

4  represents  the  cylinder-gate  operating;    in  this  case,  on  the 

inside  of  the  gate- wheel; 

5  represents  the  guide- vanes; 

6  represents  the  bottom  plate  or  ring  of  the  guide-wheel ; 

7  represents  the  top  plate; 

8  represents  the  dome  plate  of  the  guide- wheel; 

9  represents  the  box  or  lid  containing  lignum  vitas  bearing; 

10  represents  the  lignum  vitse  blocks; 

11  represents  the  lid  or  top  cover  of  the  bearing; 

12  represents  the  draft  tube; 

13  represents  the  spider; 

14  represents  the  lignum  vitse  step; 

15  represents  the  gate-rods  connecting  the  cylinder  gate  to  the 

upper  operating  device; 

16  represents  the  spur  racks; 

17  represents  the  spur  pinions  by  which  the  movement  of  the 

cylinder  gate  is  controlled ; 

18  represents  the  brackets  to  which  the  gate  rigging  is  secured ; 

19  represents  the  roller,  shown  in  the  horizontal  section,  con- 

fining the  spur  rack  to  the  spur-gear  pinion; 

20  represents  the  bevel  gear; 

21  represents  the  bevel  pinion  actuating  the  spur  pinion  and  rack; 

22  represents  the  horizontal  gate  shaft; 

23  represents  the  vertical  gate  shaft; 

24  represents  the  cable  wheel; 

25  represents  the  turbine  or  wheel  shaft ; 

26  represents  the  turbine  or  wheel-shaft  coupling; 

27  represents  the  vertical  gate-shaft  coupling; 

28  represents  the  vertical  gate-shaft  stuffing-box  located  below 

the  spur  rack; 

29  represents    the    vertical    gate-shaft    extension   finally   con- 

nected to  the  turbine  governor  or  hand  wheel; 

30  represents  the  turbine-shaft  extension. 

The  design  of  the  housing  or  casing  of  the  turbine  depends  upon  the 
method  of  operation.  When  the  water  is  supplied  to  the  turbine  by  a 
feed  pipe,  the  casing  consists  of  a  shell  completely  enclosing  the  turbine; 
when  the  turbine  is  placed  in  an  open  bay,  the  case  or  draft  chest  encloses 


294  HYDRO-ELECTRIC    PRACTICE 

all  but  the  guide- wheel  passages  through  which  the  water  finds  its  way 
into  the  runner. 

Fig.  Ill  shows  such  a  draft  chest  for  a  double  turbine;  it  is  a  cast 
of  two  parts  with  a  man-hole  in  the  top  or  dome.  The  turbine  runners 
are  inserted  at  the  ends  EE  and  the  case  is  secured  to  the  floor  structure 
by  its  bed  flange  F. 

Fig.  112  shows  the  turbines,  runners,  and  gate-wheels  assembled 
and  connected  by  one  shaft,  all  ready  to  be  placed  in  the  casing  or  draft 
chest  shown  in  Fig.  111. 

ARTICLE  82.  Description  of  a  Central-discharge  Reaction  Turbine.— 
This  type  is  of  the  general  class  of  Fourneyron  turbines;  the  runner  is 
very  shallow,  as  compared  with  that  of  the  mixed-flow  turbine;  the 
guide  passages  are  of  little  depth  and  the  guide- vanes  are  curved;  the 
water  enters  simultaneously  into  all  guide  passages  from  a  scroll-shaped 
supply  pipe  which  encircles  the  runner  and  has  openings  along  its  interior 
periphery  through  which  the  water  spouts  into  the  guide  passages;  this 
supply  pipe  gradually  decreases  in  area,  so  that  the  velocity  of  the  enter- 
ing water  is  constant  at  all  points  of  entry.  This  special  supply  feature 
has  given  to  these  turbines  the  French  name  of  volute. 

These  turbines  are  especially  adapted  to  high-entry  velocities  and 
therefore  high  heads;  such  plants  as  those  at  Trenton  Falls,  Niagara, 
and  Shawinigan  Falls  are  equipped  with  them;  the  largest  turbine  yet 
constructed  operates  at  the  latter  plant  and  is  of  this  type  with  a  capacity 
of  10,500  horse-power. 

Fig.  113  gives  a  complete  plan  of  this  type  of  turbines  as  they  are 
constructed  in  this  country. 

No.    1  represents  the  runner; 

No.    2  represents  the  guide- vanes; 

No.    3  represents  the  guide- vane  plates; 

No.    4  represents  the  supply  chamber  passing  around  the  runner; 

No.    5  represents  the  crown  plate  of  the  turbine  casing; 

No.    6  represents  the  elbow  of  the  discharge  pipe; 

No.    7  represents  the  draft- tube  ring; 

No.    8  represents  the  main-shaft  bearing; 

No.    9  represents  the  thrust  bearing; 

No.  10  represents  the  pedestals; 

No.  11  represents  the  shaft  coupling; 

No.  12  represents  the  main  shaft; 


;  -  --      > 


Double  Turbine  Draft  Chest. 


Assembled  Twin  Turbines. 


295 


296  HYDRO-ELECTRIC   PRACTICE 

No.  13  represents  the  shaft  stuffing-boxes; 

No.  14  represents  the  man  doors  in  the  case; 

No.  15  represents  the  supply  pipe; 

No.  16  represents  the  draft  tube; 

No.  17  represents  the  governor  connections; 

No.  18  represents  the  governor. 

ARTICLE  83.  Description  of  an  American  Impulse  Turbine. — In  this 
country  the  impulse  turbines,  as  a  distinct  type,  are  represented  by  that 
shown  in  Fig.  114,  consisting  of  a  wheel  or  disk  which  carries  on  its  pe- 
riphery cup-shaped  buckets,  the  whole  being  encased  and  operating  on  a 
horizontal  shaft.  The  buckets  are  of  double  cups,  the  central  partition 
splitting  the  striking  jet  in  equal  parts  as  to  volume.  The  water  spreads 
out  all  over  the  bucket  surfaces  and  is  deflected  180°  from  the  entry 
direction  when  it  drops  from  the  buckets.  This  class  of  turbines  is 
especially  adapted  to  the  highest  heads  and  is  commonly  called  the 
hurdy-gurdy  wheel. 

In  the  figure  showing  a  plan  of  it 

No.    1  represents  the  wheel  disk; 

No.    2  represents  the  wheel  buckets; 

No.    3  represents  the  wheel  shaft; 

No.    4  represents  the  ring  oil  bearings; 

No.    5  represents  the  base  plates; 

No.    6  represents  the  nozzle; 

No.    7  represents  the  gate  valve; 

No.    8  represents  the  supply  pipe; 

No.    9  represents  the  hand-wheel  stand; 

No.  10  represents  the  hand-wheel; 

No.  11  represents  the  wheel  case; 

No.  12  represents  the  floor  plate. 

ARTICLE  84.  Theory  of  the  Draft  Tube.—  The  draft  tube  is  an  air- 
tight cylindrical  extension  secured  to  the  lower  or  discharge  end  of  the 
runner.  The  theory  of  its  service  is  based  upon  the  atmospheric  pres- 
sure of  14.72  pounds  per  square  inch,  which  equals  the  weight  of  a  column 
of  water  about  34  feet  high;  in  other  words,  a  column  of  water  of  this 
height,  and  at  rest,  is  balanced  and  therefore  held  in  equilibrium  by  the 
atmospheric  pressure.  When  the  water  in  this  column  is  in  motion,  falls, 
the  head  represented  by  the  velocity  with  which  it  falls  at  the  point  of 
exit  from  the  lower  end  of  the  column  must  also  be  balanced  by  the 


297 


298  HYDRO-ELECTRIC   PRACTICE 

atmospheric  pressure,  and  the  theoretic  height  of  the  column  held  in 
equilibrium,  or  which  can  be  maintained  in  a  draft  tube,  is  then  reduced 
by  this  head. 

If  the  exit  velocity  from  a  turbine  runner  is  that  due  to  a  head  of 
•thirty  feet,  or  approximately  0.2  ^  2  g  h  =  7.2  ft.,  and  the  water  continues 
with  this  velocity  to  the  exit  end  of  the  draft  tube,  the  head  represented 
by  this  velocity  is  h  =  7.22  -f-  2g  =  0.8  ft.,  and  the  theoretic  height  of 
the  column  held  in  equilibrium  in  the  draft  tube  is  34  —  0.8. 

If  the  velocity  in  the  draft  tube  were  46.8  ft.  per  second,  then  the 
corresponding  head  would  be  h  =  46.72  -f-  64.4  =  34  ft.  (about),  and  the 
theoretic  height  of  the  column  balanced  by  the  atmospheric  pressure 
would  be  zero. 

Any  other  losses  of  head  occurring  during  the  water's  passage  through 
the  draft  tube,  as  well  as  that  represented  by  the  energy  remaining  in 
the  finally  escaping  water,  must  be  deducted  from  the  theoretical  34 
feet. 

From  the  foregoing  it  is  apparent  that  by  the  use  of  the  draft  tube 
the  exit  velocity  from  the  runner  may  be  materially  reduced  during  its 
passage  through  the  draft  tube  by  gradually  increasing  the  flow  area  in 
the  latter,  and  that  therefore  otherwise  lost  head  is  conserved  and  avail- 
able to  produce  useful  work; 

That  the  opportunity  of  gain  from  this  source  is  greater  with  a  long 
than  a  short  draft  tube; 

That  the  use  of  the  draft  tube  permits  the  placing  of  the  turbine  at 
a  convenient  height  above  the  tail  water,  while  without  it  the  turbine 
must  be  placed  at  or  below  the  lower  level; 

That  the  draft  tube  makes  it  feasible  to  place  the  turbine  on  a  hori- 
zontal shaft  at  sufficient  height  above  the  lower  pool  to  allow  of  directly 
connecting  it  to  the  electric  generator  or  other  machinery;  and  there- 
fore it  is  true  that  the  draft  tube  brought  out  the  horizontal  turbines. 

It  will  also  be  understood  from  the  theory  presented  that  draft  tubes 
cannot  be  used,  as  such,  with  impulse  turbines,  since  the  water  column 
passing  through  the  impulse  turbine  is  not  continuous. 

The  practical  application  of  the  draft  tube,  its  most  efficient  design 
and  length  under  differing  conditions,  is  fully  treated  in  a  succeeding 
article. 

ARTICLE  85.  Theory  of  Deducting  Turbine  Efficiencies. — The  useful 
work  represented  by  the  turbine  output  is  the  total  available  energy  less 


EQUIPMENT  299 

the  losses  occurring  in  the  turbine;  these  losses  are  of  three  kinds,  hy- 
draulic, mechanical,  and  un-utilized  residues.  The  first  are  of  manifold 
origin,  generally  caused  by  friction,  impact,  and  leakage;  they  are  best 
identified  by  tracing  the  water's  flow  as  it  passes  through  the  turbine. 

(a)  In  passing  through  the  guide-vanes  some  loss  is  experienced  due  to  the  friction 

of  the  passing  water  against  the  walls  of  vanes;  the  best  conditions  exist 
when  the  walls  of  the  vanes  are  parallel,  thus  avoiding  contraction  of 
the  passing  vein,  and  when  the  guide-vanes  are  made  of  hard  metal 
and  their  surfaces  are  polished.  It  is  especially  important  that  the 
guide-vanes  be  frequently  examined  and  repolished,  as  their  surfaces 
are  rapidly  roughened,  which  is  the  common  experience  when  the  water 
carries  considerable  sand  and  other  suspended  matter. 

(b)  When  passing  from  the  guide  passages  into  the  runner  the  probable  losses  are 

due  to  impact,  to  retardation,  and  to  leakage  through  the  clearance  be- 
tween the  guide-wheel  and  the  runner.  If  the  water,  upon  entering  the 
runner  buckets,  strikes  the  vanes  tangentially,  the  only  other  cause  of 
loss  from  impact  is  the  striking  of  the  edges  of  the  buckets  as  they  pass 
by  the  guide  openings;  of  course  this  can  not  be  avoided,  but  the  effect 
may  be  minimized  by  reducing  these  bucket-vane  edges  to  the  sharpest 
practical  shape  and  thus  maintaining  them.  Some  clearance  must  be 
left  between  the  guide-wheel  and  the  runner,  as  the  former  is  stationary 
while  the  latter  rotates,  and  therefore  leakage  will  take  place,  particu- 
larly as  the  interior  water  pressure  exceeds  the  exterior;  the  clearance 
should  be  a  practical  minimum,  which  necessitates  accurate  and  true 
machining  of  the  runner  bands  and  guide-wheel  plates.  This  loss  from 
leakage  through  this  clearance  is  one  which  increases  with  wear  and 
cannot  well  be  guarded  against. 

(c)  Passing  through  the  runner  the  loss  is  chiefly  that  due  to  the  friction  against 

the  walls  of  the  bucket  vanes,  which  should  be  of  hard  material  and 
polished ;  in  fact  the  conditions  here  are  analogous  to  the  passage  through 
the  guide-vanes. 

(d)  Passing  out  of  the  runner  the  principal  loss  is  caused  by  the  change  in  the 

velocity,  which  may  be  kept  at  a  minimum  by  the  proper  designing  of 
the  draft  tube. 

(e)  Passing  through  the  draft  tube  losses  are  caused  by  friction  against  the  tube's 

walls,  which  may  be  considerable,  or  very  small,  depending  solely  upon 
the  proper  design  and  construction  of  the  tube  with  a  view  of  avoiding 
joint,  rivet,  and  other  obstructions  and  maintaining  the  surfaces  as 
smooth  as  practicable  by  frequently  coating  them. 

(f)  Passing  out  of  the  draft  tube  losses  may  be  caused  by  obstructions  to  the 

free  escape  of  the  water;  the  water  cushion  below  the  draft  tube  may 
be  too  shallow,  the  tail-flume  dimensions  insufficient  or  badly  distributed. 

These  six  may  be  summed  as  the  hydraulic  losses  or  inefficiencies; 
their  aggregate  depends  upon  the  conditions  pointed  out;  when  design 
and  construction  are  the  most  suitable  for  the  purpose  and  the  best,  the 


300  HYDRO-ELECTRIC   PRACTICE 

hydraulic  losses  may  be  taken  to  aggregate  from  10  to  12  per  cent., 
while  they  may  be  double  of  this  where  design  is  faulty  or  construction 
and  finish  are  indifferent. 

The  losses  due  to  mechanical  causes  are  chiefly  those  of  friction  in 
shaft  bearings,  which  with  the  best  available  appliances  may  be  taken 
for  each  bearing  at  from  1  to  2  per  cent.,  while  it  may  be  double  or  much 
greater  when  the  true  alignment  of  the  shaft  is  permitted  to  be  disturbed. 

The  last  of  the  losses  heretofore  enumerated  is  that  represented  by 
the  unutilized  energy  remaining  in  the  escaping  water;  proper  design 
should  keep  the  exit  velocity  to  0.2  or  0.25  of  the  velocity  of  total  available 
head,  and  beyond  this  no  further  reduction  of  this  loss,  with  a  proper 
use  of  the  draft  tube,  can  be  secured.  This  last  loss  from  unutilized 
energy  will  be  from  5  to  6  per  cent. 

Summarizing  these  losses  in  reaction  turbines: 

hydraulic  losses 11  to  12  per  cent. 

mechanical  losses  for  two  bearings 2  to    4  per  cent. 

unutilized 5  to    6  per  cent. 

18  to  22  per  cent. 

representing  the  best  theoretic  conditions,  and  therefore  obtainable 
efficiencies,  of  output  of  from  78  to  82  per  cent. 

It  will  be  noted  that  two  of  the  causes  of  losses  grow  out  of  the  use 
of  the  draft  tube,  and  these  would  not  occur  were  no  draft  tube  employed; 
the  significance  of  this  applies  only  to  impulse  turbines  in  which,  for  this 
and  other  reasons,  a  considerably  higher  efficiency  of  output  can  be 
realized,  frequently  reaching  90  per  cent,  and  more. 

ARTICLE  86.  Typical  Turbine  Installations. — Reaction  turbines  may 
be  installed 

(a)  On  vertical  shaft, 

(b)  On  horizontal  shaft, 

(c)  Cased  and  supplied  through  penstock, 

(d)  Drowned  in  open  bay, 

(e)  Cased  in  pairs, 

(f)  Drowned  in  tandem, 

(g)  Drowned  side  by  side, 
(h)  Drowned  superposed. 

Impulse  turbines  are  always  placed  in  cases  and  operated  on  a  horizontal 
shaft. 


EQUIPMENT  301 

The  different  installations  of  the  reaction  turbine  are  illustrated  by 
succeeding  figures,  and  the  principal  dimensions,  such  as  are  required 
in  planning  the  power  house,  are  given  on  diagrams;  no  particular  make 
of  turbine  is  herein  referred  to,  but  the  information  in  these  figures  and 
diagrams  applies  generally  to  the  reaction  turbines  manufactured  in 
this  country  and  may  be  safely  accepted  for  the  purpose  above  indicated. 

Fig.  115  illustrates  the  vertical  turbine  drowned.  The  unit  of  this 
installation  may  consist  of  one  or  of  several  wheels;  the  generator  may 
be  coupled  to  the  vertical  shaft,  a  practice  which  is  quite  general  abroad, 
in  which  case  the  generator  operates  horizontally  and  is  sometimes  called 
the  umbrella  type.  The  installation  of  the  American  Niagara  plant  is 
of  this  arrangement.  More  frequently  the  vertical  turbine  shaft  is  geared 
to  a  driving  shaft,  the  generator  being  coupled  to  the  latter,  and  in  that 
case  several  turbines  may  be  thus  installed  in  one  power  unit,  all  being 
geared  to  a  union  shaft,  so  that  each  can  be  cut  out  separately.  The 
turbines  of  the  same  unit  may  be  placed  in  one  or  separate  bays,  the 
latter  arrangement  allowing  of  making  repairs  to  any  turbine  of  the 
multi-unit  without  stopping  the  operation  of  the  remaining  wheels. 

The  installation  of  vertical  turbines  drowned  and  geared  to  a  driv- 
ing shaft  represents  the  oldest,  the  mill-power,  practice  in  the  utilization 
of  water-power;  it  is  also  frequently  chosen  for  hydro-electric  plants, 
though  it  does  not  yield  high  output  efficiency.  Vertical  turbines,  drowned, 
with  generators  coupled  to  the  turbine  shaft,  constitute  the  latest  devel- 
oped installation,  which  is  capable  of  yielding  the  highest  obtainable 
output  efficiency  of  reaction  turbines. 

This  installation  is  suitable  for  the  lowest  and  for  high  heads,  the 
limitations  being  the  length  of  shaft,  the  weight  of  shaft,  and  the  cost 
of  open-bay  construction;  the  Niagara  installation  represents  the  high- 
head  limit,  to  the  present  time,  being  175  feet;  the  turbines,  however, 
are  not  strictly  of  the  type  here  illustrated,  but  are  double  Francis  tur- 
bines. The  lowest  head  utilized  by  a  hydro-electric  plant,  to  the  author's 
knowledge,  is  that  at  Rechtenstein,  Austria,  being  a  trifle  less  than  five 
feet;  the  turbines  are  vertical  and  drowned,  the  turbine  shaft  being 
geared  to  the  driving  shaft.  This  arrangement  is  peculiarly  adapted  to 
very  low  heads,  on  account  of  the  smaller  depth  of  the  turbine  compared 
to  its  diameter. 

The  power-house  design  suited  for  this  installation  is  described  in 
Article  76  and  illustrated  in  Figs.  84  and  88.  The  guide-wheel  rests  upon 


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304  HYDRO-ELECTRIC   PRACTICE 

supporting  frames  of  steel  members  secured  to  the  pit  structure;  the 
gearing  is  similarly  placed  on  an  upper  floor. 

Diagram  34  gives  the  approximate  exterior  dimensions  of  a  single 
vertical  turbine  drowned. 

Example. — For  a  40"  turbine  the  height  from  the  supporting  frame 
to  the  shaft  coupling,  D  in  the  diagram,  is  48";  the  diameter  of  the 
guide- wheel,  B  in  the  diagram,  is  67";  the  total  height  from  the  top  of 
the  thrust  bearing  to  the  lower  end  of  the  draft  tube,  E  +  C  in  the  dia- 
gram, is  66" ;  the  required  width  of  the  open  bay  in  which  this  turbine 
is  placed  is  2  B  or  IF  2";  the  length  of  the  bay  for  two  such  turbines 
is  double  the  width  or  22'  4". 

In  this  manner  the  dimensions  of  the  turbine  bay  for  this  installa- 
tion, and  therefore  of  the  power  house,  can  be  readily  determined  from 
this  diagram. 

In  this  category  of  turbine  installations  falls  that  of  serial  turbines, 
illustrated  in  Fig.  87  of  Article  76,  which  is  specially  adapted  to  fluctua- 
tions of  head;  in  this,  vertical  turbines  drowned  are  placed  one  above 
another,  a  separate  tail-flume  being  provided  for  each,  by  which  arrange- 
ment they  are  available  to  operate  singly  or  jointly;  this  represents  the 
only  method  at  present  known  which  solves  the  problem  of  utilizing 
excessive  head  fluctuations,  and  is  deserving  of  far  more  attention  than 
is  now  given  it  in  the  American  practice. 

Fig.  116  shows  the  installation  of  vertical  turbines  cased,  the  water 
being  supplied  through  penstocks.  The  cases  are  placed  upon  and 
secured  to  supporting  frames,  the  penstock  or  supply  pipe  entering  the 
case  at  the  side  or  top.  The  shaft  connection  and  generator  drive  are 
similar  to  those  described  for  the  vertical  turbine  drowned.  The  deter- 
mination between  the  drowned  and  cased  installation  of  vertical  tur- 
bines must  be  based  upon  the  respective  cost  of  open-bay  construction 
and  of  turbine  casing  and  penstocks;  operation  and  output  efficiencies 
are  alike  in  both.  This  installation  offers  no  special  advantages  with 
low  heads;  it  is  frequently  met  with  in  mill-power  plants,  the  turbines 
being  placed  un-housed  over  the  tail-race  and  geared  to  the  driving 
shaft  of  the  mill. 

The  dimensions  of  vertical  turbine  cases  are,  generally  speaking, 
the  same  as  those  given  for  the  open  bay  of  drowned  turbines. 

Fig.  117  illustrates  the  installation  of  a  pair  of  horizontal  turbines 
drowned. 


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307 


308  HYDRO-ELECTRIC   PRACTICE 

At  the  outset  it  may  be  stated  that  this  represents  that  type  of 
turbine  installation  best  adapted  to  low  and  medium  heads  and  is,  next 
to  the  vertical  drowned  and  umbrella  generator  plant,  of  highest  practical 
efficiency. 

The  turbine  runners  are  secured  to  the  ends  of  a  union  draft  chest, 
as  was  shown  in  Fig.  112  of  Article  81,  both  connected  to  one  shaft, 
to  which  the  generator  is  coupled  or  belt  driven  from  it  if  high  speed 
is  desired  for  it.  The  installation  is  placed  in  an  open  bay,  the  lower 
flange  of  the  draft  chest  resting  upon  and  being  secured  to  a  sup- 
porting frame  of  steel  members,  the  shaft  bearing  on  floor  stands  or 
bridge  trees.  The  gate  devices  of  both  turbines  are  operated  by  a  union 
gate  shaft  finally  connected  to  the  turbine  governor.  The  economical 
limit  of  this  installation  is  found  from  a  comparison  of  the  cost  of  the 
turbine  bay  construction  and  that  of  turbine  casings  and  penstocks 
supplying  the  water  to  them.  The  efficiency  obtainable  from  this  arrange- 
ment, as  compared  with  that  of  horizontal  turbines  cased  and  penstock 
fed,  should  be  higher,  because  of  the  loss  of  head  involved  in  supplying 
water  through  pipes. 

The  power-house  design  adapted  to  this  turbine  installation  may  be 
as  shown  in  Figs.  85  and  86  of  Article  76,  with  such  variations  in  details 
as  will  be  suggested  by  the  local  conditions  and  the  power  head. 

Diagram  35  gives  the  approximate  exterior  dimensions  of  this  instal- 
lation for  turbines  of  various  sizes,  from  which  the  required  bays  can 
be  planned. 

Example. — For  a  pair  of  35"  turbines  drowned,  the  height  from  the 
supporting  frame  to  the  centre  shaft  line,  E  in  the  diagram,  is  3'  3"; 
the  height  from  the  supporting  frame  to  the  top  of  the  draft  chest,  B  in 
the  diagram,  is  5'  8";  the  diameter  of  the  draft  tube  collar,  D  in  the 
diagram,  is  8'  5";  the  total  length  of  the  installation,  A  in  the  diagram, 
is  15'  5";  the  required  width  of  the  turbine  bay  is  2  B  or  11'  4";  the 
required  length  of  the  turbine  bay  is  A  +  5'  or  20'  5". 

Fig.  118  shows  the  installation  of  three  horizontal  turbines  drowned. 

This  is  the  same  arrangement  as  has  just  been  described,  with  the 
addition  of  the  third  wheel,  which  discharges  by  separate  draft  tube. 
The  draft  chest  of  the  single  turbine  is  of  the  quarter-turn  shape,  the 
union  shaft  penetrating  it  by  a  stuffing-box.  This  arrangement  is  as 
efficient  as  that  of  one  pair  of  turbines  and  frequently  preferable  in 
order  to  secure  a  higher  generator  speed. 


309 


310  HYDRO-ELECTRIC   PRACTICE 

The  dimensions  for  this  installation  are  found  from  Diagram  35  for 
the  pair  and  Diagram  36  for  a  single  horizontal  turbine  drowned. 

Example. — For  three  30"  turbines,  the  height  from  turbine  sup- 
porting frame  to  the  shaft  and  to  the  top  of  the  draft  chest  is  the  same 
as  that  given  for  the  double  turbine  on  Diagram  35;  the  diameter  of 
the  draft  tube  collar  for  the  single  turbine,  D  in  Diagram  36,  is  4' ;  the 
total  length  is  the  sum  of  A  on  Diagram  35  and  B  on  Diagram  36,  or 
13'  1"  +  11'  11"  =  25'  6";  the  width  of  the  required  bay  is  the  same  as 
that  for  the  double  turbine ;  the  length  of  the  turbine  bay  is  the  length 
of  the  installation  +  5',  or  30'  6". 

The  installation  may  be  of  a  single  horizontal  turbine  drowned,  as 
shown  on  Diagram  36.  In  this  case  the  open  bay  need  only  be  long 
enough  to  allow  the  water  to  enter  the  guide  wheel  as  is  indicated  by  the 
partial  bulkhead  in  the  figure  on  Diagram  36.  The  dimensions  may  be 
readily  found  from  Diagram  36. 

Fig.  119  illustrates  the  installation  of  two  pair  of  horizontal  tur- 
bines drowned. 

The  characteristics  of  this  installation  are  the  same  as  those  of  one 
pair  or  of  three  horizontal  turbines  drowned,  the  difference  being  one 
of  dimensions  only,  and  they  change  merely  as  to  the  length,  which  is 
double  that  given  on  Diagram  35. 

In  this  manner  any  number  of  turbines  can  be  united  into  one  power 
unit.  The  plant  on  the  Spring  River,  Kansas,  recently  constructed, 
consists  of  units  containing  four  pairs  of  double  horizontals  drowned. 
The  wisdom  of  such  a  long  line  of  turbines  operating  one  shaft  may  be 
questioned,  on  account  of  the  many  shaft  bearings  which  must  be  free 
to  line  to  avoid  serious  friction  losses. 

Figs.  120  and  121  show  the  installation  of  a  pair  of  horizontal  tur- 
bines cased. 

As  with  vertical  turbines,  the  installation  of  horizontals  may  be  in 
cases,  single  or  double,  supplied  through  a  penstock  entering  the  case 
at  the  top  or  at  the  end,  the  discharge  being  by  one  or  two  draft 
tubes.  This  arrangement  meets  the  requirements  of  heads  which 
exceed  the  utilization  of  the  drowned  type  and  is  available  until  the 
pressure  head  exceeds  the  economical  limit  of  turbine-case  strength. 
The  power-house  design  for  this  installation  is  shown  in  Fig.  89,  of 
Article  76. 

The  dimensions  for  this  programme  are  given  in  Diagram  37. 


20 

19 

18 

17 

16 

15 

14 

13 

12 

11 

10 

9 

8 

7 

6 

5 

4 

3 


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Diagram  36 

Single  horizontal 
Turbine,  drowned. 

Dimensions. 


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311 


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313 


314  HYDRO-ELECTRIC   PRACTICE 

Example.  —  For  two  40"  turbines  cased,  the  height  from  the  sup- 
porting frame  to  the  centre  shaft  line,  G  in  the  diagram,  is  4'  2";  the 
diameter  of  the  case,  A  in  the  diagram,  is  10'  IV]  the  total  length,  F  in 
the  diagram,  is  31'  8". 

ARTICLE  87.  Reaction  Turbine  Output.  —  The  discussions  of  the 
theory  of  turbines  in  Article  79  and  of  turbine  efficiency  in  Article  85 
have  paved  the  way  for  the  presentation  of  this  final  turbine  topic, 
"the  output,"  a  thorough  understanding  of  which  is  highly  essential 
to  determine  what  is  the  most  resourceful  hydraulic  equipment  for  a 
given  case. 

The  turbine  output  here  referred  to  is  the  power  yield  at  highest 
shaft  speed  with  the  least  quantity  of  water  at  three-quarter  gate  opening, 
which  is  the  definition  of  the  maximum  efficiency  output.  The  condi- 
tions of  this  output  are  rigid  as  to  speed,  which,  in  hydro-electric  practice, 
represents  the  first  essential,  because  the  efficiency  of  the  generator  is 
largely  based  upon  it;  in  other  words,  the  power  yield  rises  or  falls  as 
more  or  less  water  is  passed  through  the  turbine,  while  the  speed  remains 
approximately  constant. 

The  three-quarter  gate  discharge  basis  is  the  most  practical,  lying 
midway  between  full  and  half,  the  latter  being  the  low  limit  of  resource- 
ful efficiency,  while  it  provides  a  reserve  output,  from  three-quarter 
gate  to  full,  which  is  especially  valuable  in  meeting  the  frequent  increase 
of  the  generator  load.  The  discharge  from  three-quarter  to  full  gate  is 
practically  proportionate  to  the  gate  opening,  while  that  at  half  gate  is 
somewhat  in  excess  of  the  half  full  gate  discharge. 

The  efficiency  of  this  output  is  approximately  80  per  cent., 
provided  the  conditions  of  design  and  construction  on  which  it  is 
based  are  met. 

The  power  constants  here  given  are  those  of  reaction  turbines,  and 
the  values  are  those  for  one  foot  head;  they  are  distinguished  from  the 
output  of  the  same  turbine  for  more  than  one  foot  head  by  the  prime 
mark,  thus  P',  Q',  S',  representing  the  power,  discharge,  and  speed  out- 
put of  the  turbine  under  one  foot  head,  while  P,  Q,  and  S  represent  the 
output  of  the  same  turbine  for  a  greater  head  than  one  foot. 

Power,  in  mechanical  horse-power,  for  unit  head,  P',  from 


550 


x  efficiency  •-=  Q'  X  0.1136  X  0.80  =  0.09  Q'. 


315 


316  HYDRO-ELECTRIC   PRACTICE 

For  any  head  greater  than  one  foot  the  discharge  of  the  same  turbine 
increases  with  V  H,  and  the  power  output  for  any  head  H  therefore  is 

p  =  p'  x  V  H3  =  0.09  Q'  X  V  H3. 
Discharge,  in  cubic  second  feet,  from  power  constant 


For  any  head  H,  Q  =  Q'  X  V  H  =  11.1  P'  X  V  H. 

Speed,  in  revolutions  per  minute,  S',  for  unit  head,  from  the 
peripheral  speed  due  to  0.89  ^  2  g  =     7.1378  second  feet, 

or     =  428.268  minute  feet, 

and,  as  turbine  diameters  are  expressed  in  inches,  =  5,139     minute  inches, 

g,  =    5139  1635 

3.1416  "    diam.  in  inches 

Diameter  is  expressed,  as  will  be  seen  under  Design  Constants,  as 

257 
D  =  6.36  V  Q'  and  inserting  in  above  S'  =  ~7/y. 

For  any  head  H,  S  =  S'  X  V  H  =  257  V  H  +  V  Q'. 

Diagram  38  gives  the  standard  maximum  efficiency  output  of 
American  reaction  turbines,  which  are  designed  and  constructed  on  the 
general  lines  detailed  further  on. 

Example  from  Diagram  38. — For  a  35-inch  Turbine: 

Power  constant  is          2.8  mechanical  horse-power, 
Speed  constant  is         47    revolutions  per  minute, 
Discharge  constant  is  31    cubic  second  feet. 

The  output  of  the  same  (35")  turbine  for  a  16-f eet  head  is : 
Power,  constant,  X  V  163  =  179.2  m.h.p., 

Speed,  constant,  X  V  16   =  188     r.p.m., 

Discharge,  constant,     X  V  16   =  124     c.s.f. 

For  a  60-inch  Turbine: 

Power  constant  is  8.28  m.h.p., 

Speed  constant  is  27       r.p.m., 

Discharge  constant  is  92       c.s.f. 


Hor.  Turbines  cased) 
Dimensions. 


317 


318  HYDRO-ELECTRIC   PRACTICE 


The  output  of  the  same  (60")  turbine  with  a  head  of  25  feet  is : 
Power,  constant  X  V  253  =  1035  m.h.p., 

Speed,  constant  X  V  25    =     135  r.p.m., 

Discharge,  constant  X  V  25   =     460  c.s.f. 

The  efficiency  of  this  standard  output  is  (for  one-foot  head) 


from  62.5  Q'  -*-  550,  efficiency,  E  =      8.8  F 
or  =  528     P 

Applied  to  above  examples,  35"  E  =      8.8  X        2.8 
Applied  to  above  examples,  60"  E  =      8.8  X        8.28 
For  the  35"  turbine  with  16'  H,  E  =      8.8  X    179.2 


Q'  (second  feet) 
Q'  (minute  feet) 
31  =  79.32 

92  =  79.20 

124  X  16  =  79.48 


For  the  60"  turbine  with  25'  H,  E  =      8.8  X  1935.      -  460  X  25  =  79.19 

This  is  representative  of  the  degree  of  accuracy  of  deductions  taken 
from  Diagram  38,  the  standard  efficiency  being  80. 

ARTICLE  88.  Reaction  Turbine  Design. — The  elements  of  the  design  of 
the  reaction  turbine  yielding  the  standard  maximum  efficiency  output  are : 

The  diameter  in  inches,  from  the  area  required  to  pass  the  volume 

of  water  with  one-foot  head,  Q'  •*•  -^""g    =    0.1247  Q'  (c.  s.  f.), 
expressed  in  cubic  second  inches  =  17.9568  Q'  (c.  s.  f.). 

The  circular  area  which  would  pass  this  quantity  (theoretically) 

is  D2  X  0.7854  and  D2  =  17.9568  Q'  -f-  0.7854 

-  22.863    Q' 
or  D  (theoretical  diameter  of  turbine  in  inches)  =  4.78      Q'. 

To  compensate  for  the  obstructions  to  the  free  passage  of  the  water, 
the  above  theoretical  value  is  increased  by  the  coefficient  of  1.33  and 
the  turbine  diameter  =  1.33  X  4.78  VQ',  or  D  -  6.36  VQ'j_ 

The  vent  area  is  found  from  the  theoretical  velocity  -^  2  g  and  the 
coefficient  0.60,  or  for  unit  head  and  in  minute  feet  velocity,  V  =  60  X 
0.60^2  g  =  288.7  minute  feet. 

The  discharge  through  an  opening  of  one  square  inch  area  is 

288.7  -H  144         =  2  (appr.),  and  the  required  vent  area 
in  square  inches  =  60  Q'  -f-  2  =  30  Q'. 


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319 


320  HYDRO-ELECTRIC   PRACTICE 

Guide-wheel  or  gate  openings  represent  the  total  vent  area,  which 
is  generally  divided  between  12  such  openings,  the  area  of  each  is  there- 
fore =  2.5  Q'  (square  inches). 

The  dimensions  of  the  guide-wheel  or  gate  openings  are  generally  one 
of  width  to  four  of  height. 

The  runner  buckets  should  be  fewer  in  number  than  the  guide-wheel 
'or  gate  openings,  so  that  anything  which  passes  through  the  latter, 
like  chips,  ice,  etc.,  is  likely  to  pass  through  the  turbine  proper  without 
becoming  clogged  in  it. 

The  entrance  angle  to  the  runner  buckets  should  be  such  as  to  avoid 
shock  of  the  entering  water. 

The  clearance  between  the  guide  wheel  and  the  runner  should  not 
exceed  one-eighth  of  an  inch. 

The  bucket  vanes  are  of  a  helical  form,  changing  the  direction  of  the 
flowing  water  nearly  180°;  their  axial  depth  is  fixed  by  the  axial  length 
of  the  guide  openings,  for  the  axially  straight  part,  and  the  least  addi- 
tional length  which  is  necessary  to  secure  a  true  helical  curve. 

The  draft-tube  diameter  at  the  entrance  should  be  such  that  the 
velocity  does  not  exceed  five  feet;  the  exit  diameter  should  be  1.5  of 
the  entrance  diameter;  the  sum  of  the  entrance  diameter  and  the  length 
above  tail-water  should  be  approximately 

29  feet  for  diameters  up  to  two  feet, 
27  feet  for  diameters  from  two  to  three  feet, 
25  feet  for  diameters  from  three  to  four  feet, 
23  feet  for  diameters  from  four  to  six  feet, 
22  feet  for  diameters  from  six  to  twelve  feet. 

The  structural  finish  of  the  turbine  parts  should  be  as  defined  in 
Article  93. 

ARTICLE  89.  Output  of  Tangential  Impulse  Turbines. — The  efficiency 
of  this  type  of  turbines  is  somewhat  higher  than  that  of  reaction  turbines, 
owing  to  the  fact  that  the  water  does  not  pass  through  guides  and  buck- 
ets, but  is  jetted  directly  upon  the  bucket  faces;  the  hydraulic  losses 
are  therefore  much  minimized,  while  those  of  unused  energy  and  of 
mechanical  origin  are  about  the  same  as  for  the  reaction  turbines.  Draft 
tubes  are  not  of  the  same  value  with  these  turbines  as  they  are  with  the 
reaction  types,  unless  the  turbine  runner  is  housed  in  an  air-tight  casing, 


EQUIPMENT  321 

and  then  the  loss  of  head  is  that  represented  by  the  height  between  the 
elevation  of  the  nozzle  delivering  the  jet  of  water  and  the  elevation  of 
the  tail  water. 

The  constants  of  the  maximum  efficiency  output  of  tangential  tur- 
bines are  based  upon  the  standard  efficiency  of  85.  The  deductions  of 
these  constants  follow  the  same  lines  as  detailed  in  Article  87. 

Power,  in  mechanical  horse-power,  for  unit  head,  P'  =  0.0966  Q'. 
Speed,  in  revolutions  per  minute,  for  unit  head,     S'  =  10.6  -f-  V  Q'- 
Discharge,  in  cubic  second  feet,  for  unit  head,        Q'  =  10.35  P'. 

Diagram  39  gives  these  constants  for  unit  head  for  the  standard 
size  tangential  turbines  as  manufactured  in  the  United  States. 

Example  from  Diagram  30. — For  a  24-inch  Tangential  Turbine: 

Power  constant  is  0.0078  mechanical  horse-power, 

Speed  constant  is  38  revolutions  per  minute, 

Discharge  constant  is        0.08      cubic  second  feet  or 

4.8        cubic  minute  feet. 

The  output  of  this  same  24-inch  tang,  turbine  with  a  head  of  900  feet  is : 
Power,  constant          X  V  9003  =      21.06  m.h.p., 
Speed,  constant          X  V  900   =  1140       r.p.m., 
Discharge,  constant   X  V  900    =        2.4    c.s.f. 

For  a  60-inch  Tangential  Turbine: 

Power  constant  is  0.047  m.h.p., 

Speed  constant  is  15.3      r.p.m., 

Discharge  constant  is       0.49    c.s.f. 

The  output  of  this  60-inch  tangential  turbine  with  a  head  of  2500  feet : 
Power,  constant  X  V  2500  =  5875     m.h.p., 

Speed,  constant  X  V  2500  =    765     r.p.m., 

Discharge,  constant      X  V  2500  =      24.5  c.s.f. 

The  chief  elements  of  the  design  of  tangential  turbines  to  yield  the 
output  expressed  by  the  foregoing  constants  are  for 

the  diameter,  in  inches,  D  =  86.5  Q'  (Q  in  cubic  second  feet), 
the  nozzle,  in  inches,       N  =  D  -f-  18. 

Several  nozzles  may  carry  water  to  one  wheel,  as  many  as  five  being 

frequently  used,   whereby   the  same   diameter  tangential   turbine   dis- 
21 


322  HYDRO-ELECTRIC   PRACTICE 

charges  about  eight  times  the  normal  volume,  the  power  output  being 
increased  correspondingly  while  the  speed  is  slightly  lower. 

ARTICLE  90.  Summary  of  Turbine  Output  Constants.  -  -  These  con- 
stants represent  the  standard  maximum  efficiency  output  of  American 
reaction  and  impulse  turbines  at  efficiencies  of  80  and  85  respectively; 
the  expressions  are  for  unit  head,  or  a  fall  of  one  foot,  being 

power,  in  mechanical  horse-power,  with  one  foot  head,  P', 
speed,  in  revolutions  per  minute,  with  one  foot  head  S', 
discharge,  in  cubic  second  feet,  with  one  foot  head,  Q'. 

Reaction  Turbines.  Tangential  Impulse  Turbines. 
0.09  Q'                                 Power  constant  0.0966  Q' 

257  -*•  V  Q'  Speed  constant  10.6  H-  v  Q' 

11.1  P'  Discharge  constant  10.35  P' 

6.36  V  Q'  Diameter  86.5  V  Q' 

Nozzle  (single)  4.75  V  Q' 

For  any  head  H  the  corresponding  output  is  obtained  for 

Power,  from  power  constant  X  V  H3  for  reaction  and  impulse  turbines. 
Speed,  from  speed  constant  X  V  H  for  reaction  and  impulse  turbines. 
Discharge,  discharge  constant  X  V  H  for  reaction  and  impulse  turbines. 

Diameter  and  nozzles  remaining  as  per  constants. 

ARTICLE  91.  Determining  the  Turbine  Equipment.  —  As  has  been 
stated  before,  the  chief  criterion  in  selecting  the  turbine  equipment  for 
a  hydro-electric  plant  is  the  speed.  From  the  constants  in  Article  90 
it  will  be  noted  that  the  ratio  of  speed  of  reaction  and  tangential  turbines 
is  about  as  24  to  one,  and  therefore  the  first  will  prove  generally  prefera- 
ble for  hydro-electric  installations  until  the  head,  and  therefore  the 
speed,  becomes  too  high  both  for  the  reasonable  wear  of  the  turbine  and 
the  speed  standard  of  the  best  adapted  electrical  apparatus  for  the  con- 
ditions. No  demarcation  line  can,  however,  be  drawn  between  the  adapt- 
ability of  the  two  types  of  turbines  excepting  the  general  limitation  of 
the  high  head,  as  for  heads  above  300  feet  reaction  turbines  will  not 
prove  preferable  over  the  tangential;  however,  there  may  be  conditions, 
with  heads  much  lower  than  that  stated;  where  the  tangential  type 
should  be  preferred,  as  it  must  not  be  overlooked  that  from  it  can  be 
secured  an  increase  of  not  less  than  five  per  cent,  output  in  power,  which 
may,  in  small  plants,  form  the  deciding  argument. 


-•0.8 


5*0.7 


80 


45 


40 


-0.6 


—     25 
£-0.4 


8-0.3 


15 

—0.2 
Z     10 

—0.1 


Diagram  39. 

Tangential 
Impulse  Turbine, 

Maximum 
Efficiency  Output. 


£ 


^5r 


H.E.P. 


H.  v.  S. 


0.07  ~ 

0.0651 

0.06- 

0.055- 

0.05 

0.045Z 

0.04  Z 

0.0351 

0.03  Z 

0.025- 

0.02  — 

0.0  ir 

O.OlZ 

0.005^ 


24 


36  Diameter     48 


60 


72 


323 


324  HYDRO-ELECTRIC    PRACTICE 

The  power  functions,  available  head  and  flow,  being  known,  the 
constant  output  discharge  volume  is  found  by  dividing  available  flow 
by  V  H;  this  is  the  value  of  Q',  and  the  investigation  is  ready  for  con- 
sultation of  Diagram  38  or  39,  as  the  head  may  be  low  or  medium  or  high. 

Example  1. — Available  flow  is  460  c.s.f.  and  head  is  16  ft. 

Q'  =  460  H-  V16  =  115. 

If  this  quantity  is  outside  of  the  diagram  scope,  it  exceeds  the  dis- 
charge output  of  a  commercially  standard  reaction  turbine,  and  it  must 
therefore  be  reduced  by  division  into  the  least  number  of  parts  required 
to  bring  the  unit  quantity  within  the  limit  of  the  diagram. 

Returning  to  Example  1,  the  unit  discharge  of  115  c.  s.  f.  is  found 
on  the  left-hand  index  and  traced  to  the  right  until  the  discharge  curve 
is  intersected,  thence  leading  downward  to  the  lower  index  where  the 
turbine  size  is  found  of  which  this  quantity  is  the  discharge  constant, 
and  from  this  to  the  intersections  of  the  dimension  index  with  the  power 
and  speed  curves  these  constants  are  obtained,  and  from  them  the  out- 
put for  the  available  head  of  16  feet.  In  this  case  a  67-inch  turbine 
represents  this  discharge,  and  its  constants  are: 

P'  =    10.5         S'  =  24.5        Q'  =  115, 
and  the  16-ft.  output,  P   =  672  S   =  98  Q   =  460; 

the  speed  is  therefore  98  revolutions,  which  is  too  low  for  direct  con- 
nected electric  apparatus. 

Taking  half  of  the  unit  discharge,  58  c.  s.  f.,  Diagram  38  gives  a 
48-inch  turbine  which  .meets  it ;  the  output  constants  are : 

P'  =      5.25        S'  =36        Q'  =    58, 
the  16-ft.  output  P   =  336  S   =  144        Q   =  232. 

If  this  speed  of  144  r.  p.  m.  is  still  too  low,  one-fourth  of  the  flow  constant 

is  taken  or  29  c.  s.  f.,  for  this 

Diagram  38  gives  a  34-inch  turbine;   the  output  constants  are: 

P'  =      2.6        S'  =    49  and  Q'  =    29, 
the  16-ft.  output  is  P   =  166.4        S   =  196         Q   =  116. 

Two  34"  turbines  in  one  unit  yield  332.8  m.  h.  p. 


EQUIPMENT  325 

The  ratio  of  turbine  diameters  as  above,  67,  48,  and  34,  is  the  con- 
stant representing  the  ratio  of  the  diameter  of  one  large  turbine  to  the 
diameter  of  two  smaller  turbines  with  like  power  output,  and  vice  versa, 
which  is  expressed  approximately  by 

D  =  1.42  d    and    d  =  0.71  D. 

Example. — The  power  yield  of  one  54-inch  turbine  is  equalled  by  that 
of  two  38-inch  turbines  from  54  X  0.71,  and  the  power  yield  of  two  23- 
inch  turbines  is  equalled  by  that  of  one  33-inch  turbine,  from  23  X  1.42. 

The  final  comparative  factors  are  speed  and  output  expressed  in 
terms  applied  to  the  commercial  standard  types  of  generators,  that 
is  kilowatt,  in  accordance  with  the  maximum  efficiency  output  of  tur- 
bines, which  is  higher  than  the  water-power-electric  power  ratio  given 
in  Diagram  3  of  the  first  part  of  this  volume,  where  a  lower  turbine 
efficiency  was  adopted  in  order  to  secure  safe  conservative  estimates  for 
the  preliminary  investigation  of  a  hydro-electric  opportunity. 

The  following  arrangement  may  be  found  convenient  for  the  equip- 
ment determination. 

Q  H  D  P                     S  K.W. 

Available  1 200  36 

Unit.  200  1                                                                                    Per  unit.  Total. 

One  turbine . .  90" 

Two  turbines  @ 600  36  64"  1,944  153  1,376  2,752 

Three  turbines  @....  400  36  52"  1,296  188  917  2,751 

Four  turbines  @ 300  36  45"  972  218  688  2,752 

Five  turbines  @ 240  36  40"  778  245  550  2,750 

Six  turbines  @ 200  36  37"  648  265  459  2,754 

Seven  turbines  @  ...  171  36  34"  561  294  397  2,779 

Eight  turbines  @...  .  150  36  31"  475  324  346  2,768 

Nine  turbines  @ 133  36  29"  432  336  305  2,752 

Ten  turbines  @ 120  36  28"  388  360  275  2,750 

Eleven  turbines  @  .  .  109  36  27"  356  372  252  2,772 

Twelve  turbines  @  . .  100  36  25"  324  396  229  2,748. 

From  this  analysis  of  turbine  output  all  feasible  unit  combinations 
can  be  drawn: 

Speed.  Unit  output- 
Twelve  units  of  single 25"  396  229/ 

Six  units  of  double 25"  396  458 

Five  units  of  double 28"  360  550 

Four  units  of  double : 31"  324  692 

Four  units  of  three 25"  396  687 

Three  units  of  four 25"  396  916 

Three  units  of  three 29"  336  905 

Two  units  of  three 37*  265  1,377 

Two  units  of  two 45"  218  1,376 

Two  units  of  single 64"  153  1,376 


326  HYDRO-ELECTRIC    PRACTICE 

This  represents  all  the  practicable  turbine  combinations  for  this  set 
of  conditions,  covering  a  range  of  speed  from  153  to  396  and  of  genera- 
tors from  229  to  1376  K.W.  capacity,  and  it  exhausts  the  investigation 
at  the  turbine  end  of  the  equipment,  and  is  continued  by  the  further 
examination  of  standard  generator  units  and  the  final  selection  of  such 
an  arrangement  as  best  harmonizes  the  three  factors, — market  require- 
ments, turbine,  and  generator  adaptability. 

With  high  heads,  of  300  feet  and  more,  the  same  process  is  extended 
to  tangential  impulse  turbines,  in  which  Diagram  39  may  be  utilized; 
here  the  scope  of  possible  combinations  is  somewhat  narrower,  unless 
the  feasibility  of  supplying  the  water  by  more  than  one  jet  is  taken  into 
consideration,  which  leads  into  the  volute  or  central  discharge  turbine, 
types  more  frequently  employed  abroad,  but  which  may  now  also  be 
procured  in  this  country,  and  represents  the  high  efficiency  of  the  tangen- 
tial turbines  coupled  with  a  large  discharge  capacity. 

ARTICLE  92. — Turbine  governors  are  required  in  connection  with  the 
operating  of  the  turbine  equipment  of  a  hydro-electric  plant  when  the 
head  or  the  work  to  be  done  by  the  generated  power,  the  load,  fluctuates ; 
one  or  both  of  these  conditions  prevail  in  probably  every  hydro-electric 
power  plant.  Like  other  governors,  turbine  governors  are  expected  to 
regulate  the  volume  of  the  power-generating  substance,  in  this  case  the 
water,  which  regulation,  in  reaction  turbines,  must  be  applied  at  the 
turbine  gates,  controlling  the  gate  openings,  while  in  impulse  turbines 
of  the  tangential  type,  where  the  water  is  supplied  to  the  buckets  by  the 
way  of  a  nozzle,  the  regulation  by  the  governor  must  be  of  the  nozzle's 
opening,  which  is  generally  secured  by  the  axial  movement  of  a  plug  or 
needle  passing  in  the  interior  of  the  nozzle  back  or  forth  as  actuated  by 
the  governor's  movements.  These  conditions  are  widely  different  from 
those  prevailing  in  the  regulation  of  steam-engines,  steam  being  elastic 
and  compressible,  while  water  is  not ;  the  steam  valves  to  be  operated  by 
the  governor  being  accurately  fitting  machinery  parts  easily  moved  and 
controlled,  while  the  gates  of  turbines  are  large  and  heavy,  and  certainly 
not  to  be  compared  in  fit  and  finish  of  motion  to  the  valve;  a  turbine 
gate  is  exposed  to  the  water  pressure  and  when  once  set  in  motion  is  not 
readily  stopped  or  controlled.  All  these  conditions  make  it  necessary 
that  a  turbine  governor  be  supplied  with  some  other  source  of  energy, 
to  be  applied  to  the  regulating  of  turbine  gates,  than  that  represented 
by  the  usual  centrifugal  balls  of  the  steam  governor,  and  all  turbine 


ca 


— jW- 


Tvl 

'OR  SuPPL' 
«?J  Pl»C  TXP  F0«  Ej'l-IAOST 


Figure    123 


Sturgess  Governor 


EQUIPMENT  327 

governors  have  such  additional  power  source  made  available  through 
the  initiative  of  the  centrifugal  speed  regulation.  This  is  the  relay  energy 
source  of  the  governor,  and  may  be  of  mechanical,  hydraulic,  electric, 
or  pneumatic  origin,  the  first  two  being  those  applied  in  American  practice. 

The  manufacture  of  governors  of  this  class  is  restricted  in  this  country 
to  a  few*  concerns,  and  it  will  serve  the  purpose  best  to  describe,  very 
briefly,  the  pertinent  characteristics  of  the  different  types,  which  here 
follow;  the  illustrations  of  these  governors  have  been  furnished  by  the 
respective  makers  of  the  machines. 

The  Lombard  governor  is  manufactured  by  the  Lombard  Governor 
Company,  at  Ashland,  Mass. ;  it  is  of  the  hydraulic  type. 

Fig.  122  shows  the  elevation  of  one  of  the  several  types  and  a  section 
with  the  dimensions  of  the  important  features. 

This  governor  consists  of  the  following  parts:  A  centrifugal  speed 
regulator,  a  regulating  valve  with  adjustable  valve  stem,  a  pressure  tank 
and  receiver,  a  hydraulic  cylinder,  power  pump,  antiracing  mechanism, 
and  terminal  connections  of  racks,  pinions,  clutch,  and  hand-wheel  shaft. 

The  governor's  operation  is  briefly  described  thus:  The  centrifugal 
head  is  connected  to  a  regulating  valve  by -a  valve  stem  in  two  parts 
connected  by  a  screw  coupling,  which  is  adjustable  and  whereby  the 
normal  governor  speed  may  be  fixed  or  altered.  The  fluctuation  of  the 
centrifugal  head  actuates  the  regulating  valve,  which  permits  fluid  under 
pressure  to  pass  from  a  pressure  tank  to  the  hydraulic  cylinder  which 
controls  the  gate  operations.  The  oil  is  pumped  into  the  pressure  tank 
by  a  suitable  force  pump;  where  high  pressure  heads  are  available, 
water  pressure  may  be  utilized ;  the  oil  which  is  exhausted  by  the  hydrau- 
lic cylinder  passes  back  into  the  receiver  from  whence  it  is  again  returned 
by  the  pump  to  the  compressor  tank;  in  this  manner  the  relay  energy 
is  practically  maintained  constant.  • 

The  Sturgess  governor  is  also  of  the  hydraulic  type;  it  is  manufactured 
by  the  Ludlow  Valve  Manufacturing  Company,  at  Troy,  N.  Y. 

Fig.  123  shows  this  type  of  governor  in  elevation.  It  consists  of  a 
centrifugal  governor,  a  pilot  valve  operated  by  the  centrifugal  governor, 
an  operating  cylinder  controlled  by  the  pilot  valve  and  operating  puppet 
valves  of  the  main  cylinder,  a  system  of  floating  levers  between  the 
operating  cylinder  and  the  puppet  valves,  puppet  valves  which  control 
the  pressure  in  the  main  cylinder,  a  main  cylinder  with  piston,  rack, 
and  pinion  operating  the  gate  shaft,  and  a  compensator  to  prevent  racing. 


328  HYDRO-ELECTRIC   PRACTICE 

The  above  outline  of  the  principal  parts  practically  describes  the  operat- 
ing method.  The  centrifugal  governor  is  belted  to  the  turbine  shaft, 
the  pulleys  being  proportioned  to  secure  the  desired  speed  of  the  gov- 
ernor; when  the  governor  operates  at  the  normal  speed,  the  pilot  valve 
stands  between  the  two  ports  of  the  operating  cylinder,  while  the  smallest 
deviation  from  normal  speed  raises  or  lowers  the  pilot  valve  and  affords 
a  passage,  to  the  fluid  under  pressure,  to  the  hydraulic  cylinder  connected 
to  the  turbine  gate  shaft. 

The  Woodward  governor  is  manufactured  by  the  Woodward  Gov- 
ernor Company,  of  Rockford,  111.  It  is  a  mechanical  governor — that  is, 
the  relay  energy  is  of  mechanical  source. 

Fig.  124  shows  the  elevation  of  this  governor,  known  as  the  com- 
pensating type.  The  power  which  operates  the  governor  is  taken  from 
the  turbine  shaft  by  a  belt  to  a  pulley  on  the  main  governor  shaft,  to 
which  a  double  bevelled  friction  wheel  is  keyed  through  which  the  power 
for  the  gate  operation  is  applied.  The  friction  wheel  is  made  of  compressed 
paper.  On  both  sides  of  the  friction  wheel  are  friction  pans  whose  faces 
are  of  the  same  bevel  as  those  of  the  friction  wheel ;  one  of  these  friction 
pans  effects  the  opening,  the  other  the  closing,  of  the  turbine  gates.  The 
friction  pans  are  pressed  into  the  hubs  of  spur  pinions  which  run  free 
on  the  governor  shaft  and  engage  with  gears  of  a  back  shaft,  one  direct 
and  the  other  through  an  intermediate  gear.  Friction  wheels  and  pans 
are  cleared  by  adjusting  rollers.  The  governor's  regulating  action  is 
initiated  by  the  centrifugal  balls,  their  deviation  from  normal  speed 
forcing  the  friction  wheel  against  the  respective  friction  pan  and  this  in 
turn  acting  upon  the  gate  operating  shaft.  The  governor  is  self-contained, 
consisting  of  the  following  principal  parts :  a  revolving  double  feed  cam, 
a  vertical  rock  shaft,  a  main  friction  shaft,  a  speed  governor,  a  compen- 
sating device,  a  friction  wheel,  and  the  friction  pans,  with  gears,  pinions, 
and  connections. 

The  Lombard-Replogle  governor  is  manufactured  at  the  Replogle 
Governor  Works,  at  Akron,  Ohio;  it  is  a  mechanical  governor. 

Fig.  125  shows  the  elevation  of  this  governor,  in  which  the  speed 
governor  is  of  the  horizontal  type,  being  placed  in  the  main  pulley  which 
is  driven  from  the  turbine  shaft.  The  action  of  the  speed  governor  is 
to  press  friction  wheels  into  -contact  at  any  deviation  from  the  normal 
speed,  when  the  power  developed  from  these  primary  or  tripping  disks 
brings,  the  secondary  or  main  operating  drive  into  action.  The  main 


FIG.  124. — Woodward  Governor. 


j^ 

OF  THE  \ 

UNIVERSITY   1 

OF  I 


EQUIPMENT  329 

drive  consists  of  two  concave  disks  which  are  lined  with  leather  and 
which  rotate  in  opposite  directions  and  engage  a  spherical  pulley  placed 
concentrically  between  them.  The  tripping  frictions  force  this  spherical 
pulley  out  of  the  centres  of  the  leather-lined  friction  disks,  causing  con- 
tact with  the  moving  surfaces  and  imparting  the  power  which  operates 
the  turbine  gates.  The  movement  of  the  spherical  pulley  in  any  direc- 
tion returns  it  to  its  normal  position  at  the  centre  of  the  friction  disks, 
this  being  its  position  of  rest.  In  addition  to  the  effect  of  the  primary 
disks  in  forcing  the  spherical  pulley  out  of  the  centre  of  the  friction  disks, 
it  also  neutralizes  the  speed  of  the  governor  balls  and,  it  is  claimed, 
prevents  hunting  or  racing. 

This,  like  any  of  the  other  turbine  governors,  may  be  regulated, 
as  to  the  standard  speed  of  the  governor  element,  by  electric  devices 
operated  from  the  switchboard  of  the  operating  station. 

The  power  required  to  operate  turbine  gates  depends  upon  so  many 
different  conditions  that  a  practical  formula  cannot  be  developed.  From 
extensive  experiments  made  with  turbines  fitted  with  balanced  swinging 
or  wicket  gates,  which  were  carried  on  under  the  supervision  of  the  author, 
it  was  found  that  the  power  required  to  operate  the  gates  of  33-inch 
reaction  turbines  under  a  head  of  16  feet,  from  their  closed  to  their  full 
open  position,  was  500  foot  pounds;  with  gates  of  the  same  type  and 
correctly  swung  and  balanced  this  power  will  vary  directly  as  the  head 
and  as  the  cube  of  the  gate's  axial  diameter.  Cylinder  gates  require 
more  power,  and  there  are  other  styles  of  turbine  gates  which  take  still 
more,  though  these  are  becoming  obsolete. 

Governing  tangential  impulse  turbines  is  now  generally  accomplished 
by  regulating  the  area  of  the  nozzle  through  the  medium  of  a  plug  or 
needle  operating  axially  in  its  interior.  This  may  be  accomplished  by 
any  of  the  governors  described,  or  by  a  specially  designed  hydraulic  or 
electric  motor  secured  directly  to  the  terminal  of  the  supply  pipe  near 
the  nozzle.  Considerations  of  equally  great  importance  in  connection 
with  the  governing  of  these  types  of  turbines  relate  to  the  necessary 
compensation  in  the  supply  pipe  for  the  sudden  changes  and  speeds  of 
the  volume  of  the  water  passing  through  it  and  which  will  be  conse- 
quential of  the  governing  method,  that  is  the  regulation  of  the  volume  sup- 
plied to  the  turbine  buckets  by  the  way  of  the  jet  issuing  from  the  nozzle. 
It  needs  no  specific  discussion  to  point  to  the  dangerous  conditions  which 
may  be  created  for  the  safety  of  the  supply  pipe  and  its  connections. 


330 


HYDRO-ELECTRIC    PRACTICE 


Figure    126 


Hydraulic  relief  valves  may  be  placed  near  the  nozzle  and  connected 
to  the  supply  pipe,  or  a  by-pass  actuated  by  a  valve  responding  to  an 
excess  pressure;  stand-pipes  are  also  effective  in  protecting  the  supply 
system.  Of  all  these  the  hydraulic  relief  valve  is  to  be  preferred; 
the  by-pass  incurs  a  considerable  waste  of  water  which,  in  high-head 

developments,  needs  to  be  conserved,  and 
the  stand-pipe  will,  as  a  rule,  entail  con- 
siderable expense. 

ARTICLE  93.  Electric  Equipment; 
Magneto-dynamic  Theory. — Electric  power 
is  the  measure  of  the  useful  dynamic  work 
of  magneto-electric  energy,  which  is  the 
product  of  electro-motive  force  and  elec- 
tric current.  Electro-motive  force  is  the 
expression  of  stress  due  to  the  difference 
in  potentiality  of  the  magnetic  flux  of  sep- 
arate bodies  which  are  brought  within 
each  other's  sphere  of  influence.  The 
magnetic  flux  consists  of  the  magnetic 
waves  streaming  from  and  surrounding 
the  source  and  seat  of  magnetism;  the 
sphere  of  this  flux  is  the  magnetic  field. 

Fig.  126  represents  the  field  of  a 
magnet;  it  shows  the  streaming  forth  of 
the  magnetic  flux  from  one  pole,  the 
north,  spreading  out  over  more  or  less 
space  around  the  body  of  the  magnet, 
the  core,  returning  reassembled  into  the 
other  pole,  the  south,  and,  presumably, 
passing  through  the  core  back  to  the 

north  pole.     If  the  two  poles  are   connected  by  a  piece  of  metal,  the 
keeper,  no  evidence  of  the  flux  can  be  traced. 

Alessandro  Volta,  an  Italian  physicist  (1745-1827),  and  Luigi  Galvani, 
of  Bologna  (1737-1798),  jointly  discovered  that  two  dissimilar  metals, 
or  a  metal  and  a  metalloid,  are  capable  of  forming  an  electric  source 
when  dipped  into  an  electrolyte,  or  will  produce  a  difference  of  electrical 
potential  by  mere  contact.  This  is  voltaic  electricity.  Many  substances 
become  electrified  by  friction,  from  which  indeed  the  name,  from  electrum 


208 


EQUIPMENT 


331 


Figure     127 


or  amber,  a  material  especially  susceptible  to  electrification  by  friction. 
Electricity  thus  created  may  be  conducted  through  proper  mediums- 
copper,  silver,  aluminum — -and  becomes  the  electric  current. 

Fig.  127  represents  a  conductor  carrying  an  electric  current,  by  which 
it  becomes  the  source  and  core  of  a  magnetic  field  surrounding  it  in  a 
manner  analogous  to  that  of  the  magnet  shown  in  Fig.  126,  the  flux 
taking  the  general  shape  and  characteristic  of  circular  whirls;  in  fact 
the  electricity  or  current  appears  to  reside  largely  in  this  flux,  which, 
upon  a  rupture  of  the  conductor,  retreats  into  the  core  and  manifests 
itself  by  the  spark  which  escapes  at  the  point  of  the  conductor's  break. 

When  a  conductor,  carrying  an  elec- 
tric current,  is  wound  about  a  piece  of 
magnetizable  metal,  the  latter  becomes 
a  magnet  and  displays  all  the  charac- 
teristics above  described;  or,  if  such  a 
piece  of  metal  is  pushed  into  the  interior 
of  a  conducting  coil  carrying  an  electric 
current,  the  piece  likewise  becomes  a 
magnet.  From  these  phenomena  it  is 
deduced  that  the  molecules  of  certain 
matter,  especially  metals,  are  individual 
magnets  resting  normally  in  an  unhar- 
monious  state,  that  is  their  pole  direc- 
tions are  not  continuous,  and  that  the  influence  of  the  electric  current, 
and  the  accompanying  magneto-electric  flux,  orders  these  molecules  into 
a  complete  chain  of  magnets,  thus  opening  the  way  for  the  flow  of 
magnetic  lines  through  the  matter  and,  therefore,  the  appearance  of 
the  magnetic  flux  around  and  about  the  magnet.  Michael  Faraday, 
an  English  physicist  (1791-1867),  discovered  that  the  moving  of  a 
conductor  through  a  magnetic  field  and  crossing  the  lines  of  force 
induces  electro-motive  force  in  the  conductor  in  direction  at  right  angles 
to  that  of  the  conductor's  motion  and  to  the  lines  of  force  cut  by  it. 

This  is  the  basic  principle  of  electric  generators  and  motors, — that 
is,  converting  mechanical  energy  into  electric  current,  or  vice  versa,  by 
means  of  magneto-electric  energy  induced  by  the  moving,  generally 
rotary,  of  a  system  of  electric  conductors  through  magnetic  fields. 

.  Magneto-electric  Units. — The  flux  lines  passing  through  the  air  space 
of  a  magnetic  field  are  the  lines  of  force,  the  magneto-electric  energy 


H.E.P. 
H.  v.  S. 


209 


332  HYDRO-ELECTRIC   PRACTICE 

finds  its  origin  in  the  influence  of  these  lines,  and  the  force  they  represent 
upon  bodies  susceptible  to  such  influence  and  which  cross  their  paths, 
their  aggregate,  the  magnetic  flux,  is  denoted  by  "N,"  being  the  measure 
of  the  total  number  of  lines  of  force,  which,  as  appears  from  Fig.  126,  is 
the  same  along  any  direction  across  their  path.  The  lines  passing  through 
the  magnet  proper  are  the  magnetic  lines,  which  are  measured  by  the 
number  in  a  unit  cross-sectional  area,  one  square  centimetre,  of  the 
core,  and  are  denoted  by  "B"  or  flux  density.  The  magneto-motive 
force  emanating  from  the  magnetic  flux  is  denoted  by  "H,"  and  is  meas- 
ured by  the  C.  G.  S.  (centimetre-gramme-second)  work  unit,  the  dyne,  a 
force  which  imparts  a  velocity  of  one  centimetre  in  one  second  to  a  mass 
of  one  gramme;  a  unit  magnetic  pole  is  one  which  repels  a  pole  of  equal 
strength,  at  a  distance  from  it  of  one  centimetre  and  in  air,  with  the 
force  of  one  dyne;  a  field  of  unit  intensity  exists  therefore  at  a  distance 
of  one  centimetre  from  a  unit  magnetic  pole.  The  functions  relating 
to  the  generating  and  conducting  of  electric  currents  are  somewhat 
analogous  to  those  concerned  with  the  flow  of  water,  pressure,  volume, 
and  friction  of  conduit  being  typified  by  (pressure)  electro-motive  force, 
(volume)  current,  and  (friction)  resistance  in  the  conductor. 

The  unit  measure  of  electro-motive  force,  or  electric  pressure,  is 
the  volt  (after  Volta),  which  represents  that  force  induced  in  a  conductor 
cutting  100,000,000  lines  of  force  in  one  second;  its  symbol  is  E.  M.  F. 
or  "E." 

The  unit  measure  of  current  is  the  ampere,  named  so  by  the  Inter- 
national Electrical  Congress  at  Paris  in  1881,  in  honor  of  the  celebrated 
French  electrician  Andre  Marie  Ampere;  this  unit  represents  a  rate  of 
flow,  or  transmission  of  electricity,  which  will  pass,  with  the  pressure  of 
one  volt,  through  a  conductor  whose  resistance  is  unity;  it  is  symbolized 
by  "C." 

For  the  resistance  unit  the  ohm  was  adopted  by  the  International 
Electric  Congress  in  1893,  in  honor  of  Dr.  G.  S.  Ohm;  this  represents 
such  a  resistance  of  the  conductor  as  will  limit  the  flow  of  electricity 
under  pressure  of  one  volt  to  a  current  of  one  ampere;  its  sign  is  "R."' 

Therefore          E  =  C  X  R,         C  =  E  ^  R,         R  =  E  -^  C. 

The  electric  energy  or  power  unit  is  the  watt,  named  in  honor  of  the 
Scottish  engineer  and  inventor  James  Watt  (1736-1819),  which  represents 


EQUIPMENT  333 

that  rate  of  work  resulting  from  unit  current  flowing  under  unit  pressure, 
therefore  also  called  the  volt-ampere. 

One  watt  equals  1  -5-  746  horse-power,  or 

one  electric  horse-power,  Ehp  =  746  watts  and 

1000  watts  are  one  kilowatt. 

The  electro-motive  force  represents  the  origin  of  the  final  output, 
its  advent  through  induction,  just  as  the  head  in  hydraulics  renders  the 
flow,  or  the  current,  available;  and,  since  its  magnitude  is  proportional 
to  the  number  of  force  lines  cut  in  a  given  time,  it  is  evident  that  it  de- 
pends upon  the  three  functions,  force  lines,  conductor,  and  movement. 

"  N,"  the  number  of  force  lines  cut  in  one  second,  depends  upon  the 
section,  the  magnetic  permeability,  and  the  magnetization  of  the  magnet. 
The  section  may  be  any  which  adapts  itself  to  the  purpose;  generally 
speaking,  it  is  a  good  feature  of  a  dynamo  to  have  the  field  magnet  or 
magnets  of  super-large  section ;  the  field  may  be  that  of  several  magnets 
of  suitable  form  and  conveniently  placed  for  the  economic  and  efficient 
design  of  the  machine.  The  magnetic  permeability  of  the  materials 
used  for  dynamo  magnets  differs  considerably;  wrought  iron  probably 
is  of  the  highest  degree,  followed  by  cast-iron  and  mild  steel.  The  mag- 
netization may  be  to  any  degree  within  the  limit  of  saturation;  it  is  pro- 
vided by  passing  conductors  around  the  magnet  core,  and  its  measure  is 
expressed  in  ampere-turns,  which  represents  the  unit  of  magneto-motive 
force  and  is  equal  to  that  produced  by  a  current  of  one  ampere  flowing 
around  a  single  turn  or  spiral  of  the  conductor  and  is  denoted  by  "C  S." 

"Z,"  the  second  function  of  electro-motive  force,  is  the  number  of 
conductors  which  cut  the  lines  of  force;  they  may  be  as  numerous  as 
the  machine's  arrangement  will  allow;  Z  represents  the  number  of  con- 
ductors connected  in  series. 

The  third  function,  "n,"  relates  to  the  motion  or  movement  of  the 
conductor,  and  therefore  is  a  question  of  speed  and  of  mechanical  con- 
sideration chiefly. 

The  theoretical  magnitude  of  the  electro-motive  force  is  expressed  by 


E  = 


n  X  Z  X  N  +  100,000,000,  or     =  n  X  Z  X  N  -T-  10" 


ARTICLE  94.  Some  Current  Symptoms. — Alternations. — As  the  electro- 
motive force,  and  therefore  the  current,  finds  its  origin  in  magnetic 


334 


HYDRO-ELECTRIC   PRACTICE 


Figure    128 


stresses,  it  follows  that  it  will  fluctuate  in  magnitude  and  change  in  direc- 
tion as  the  number  of  force  lines  traversed  by  the  conductor  increases 
or  decreases,  and  that  therefore  the  generated  current  alternates. 

Fig.  128  illustrates  the  simplest  method  of  current  generating  by 
one  conductor,  being  a  loop,  revolving  axially  between  the  two  pole 

faces  of  a  magnet.  Reference  to  Fig.  126 
of  the  general  grouping  of  the  lines  of  force 
makes  it  clear  that  when  the  loop  is  in 
the  vertical  position  it  embraces  the  least 
number  of  force  lines;  while  turning 
through  a  right  angle  the  number  of  lines 
cut  by  the  conductor  gradually  increases, 
and  they  become  greatest  when  the  loop 
reaches  the  horizontal  position;  during 
this  path  the  electro-motive  force  has 
constantly  risen  and  has  maintained  the 

same  direction.  Descending  through  the  second  quarter  turn,  the  num- 
ber of  force  lines  cut  by  the  conductor  decreases  until  the  vertical 
position  is  reached  and  with  it  the  low  point  of  magnitude.  Rising 
through  the  third  and  fourth  quarters  the  same  process  is  repeated. 


H.E.P. 
H.  v.  S. 


210 


Figure    129 


H.E.P. 
H.v.  S. 


211 


Fig.  129  shows  diagrammatically  the  linear  development  of  these 
alternations  of  the  current  in  magnitude  and  direction  during  one  com- 
plete revolution  of  the  conductor;  the  horizontal  line  corresponds  to 
the  vertical  position  of  the  conductor  as  above  described,  the  upper  and 
lower  points  typify  the  horizontal  position  of  the  conductor.  The 


EQUIPMENT 


335 


Figure    130 


movement  of  any  fixed  point,  "P,"  may  be  traced  around  the  circum- 
ference of  a  circle  the  radius  of  which  corresponds  to  the  amplitude 
of  the  highest  point  which  is  reached  by  the  current's  magnitude,  and 
from  this  it  is  apparent  that  the  electro-motive  force  at  any  point,  or 
at  any  period  of  time,  in  the  path  of  the  alternating  current  equals  the 
sine  of  the  angle  through  which  the  conductor  has  turned  from  its  initial 
vertical  position. 

Frequency. — The  current  wave  due  to  one  complete  revolution  of 
the  conductor  is  called  a  period,  and  the  number  of  periods  occurring  in 

one  second  are  denominated  the  periodicity     _____ 

or  the  frequency,  or  the  cycle  of  alterna- 
tions, and  are  symbolized  by  "n."  The 
frequencies  equal  the  product  of  conductor 
revolutions  per  second  and  the  number  of 
the  field  magnets  passed  by  the  conductor 
during  one  complete  revolution. 

Example. — With  a  speed  of  conductors 
of  240  revolutions  per  minute,  or  6  per  sec- 
ond, a  six-pole  (3  magnets)  dynamo  will 
generate  current  of  18  frequencies. 

Phase. — When,  as  in  Fig.  128,  one  con- 
ductor is  provided  for  each  magnet,  being 
a  group  of  conductors  for  each  pole,  the 
alternations  of  the  current  are  monophase, 
—that  is,  there  is  one  phase  only  in  the 
complete  period ;  if,  however,  the  number  of  conductors  is  doubled,  a  two- 
phase  current  results,  and  three-phase  when  six  groups  of  conductors  are 
provided. 

Fig.  130  shows  the  two-  and  three-phase  current  waves,  the  alterna- 
tions in  the  first  being  of  quarter  periods,  or  the  phase  angle  90°,  while 
in  the  three-phase  current  the  alternations  differ  by  60°.  Any  alternat- 
ing current  other  than  single-phase  is  called  polyphase. 

Inductance,  Self-induction,  Reaction. — As  has  been  shown  in  Fig.  127, 
a  conductor  carrying  an  electric  current  is  surrounded  by  a  magnetic 
field,  and,  according  to  the  general  theory  of  the  origin  of  electro-motive 
force  being  due  to  magnetic  stress,  it  is  evident  that  the  current  carried 
by  the  conductor  will,  when  brought  into  the  sphere  of  another  magnetic 
field,  undergo  changes  corresponding  to  the  relative  stress  conditions. 


H.E.P. 
H.v.  S. 


336  HYDRO-ELECTRIC    PRACTICE 

Such  an  influence  upon  a  conductor  is  called  inductance,  and  manifests 
itself  in  destroying  the  harmonious  flow  of  volts  and  amperes  by  the 
reaction  of  the  self-induced  electro-motive  force  and  its  retardation  of 
the  current's  phase,  the  amperes,  which  fall  behind  the  volts,  this  con- 
.dition  being  called  the  lag;  the  extent  of  this  disturbance  is  expressed 
by  the  angle  of  lag,  which  is  the  measure  of  that  portion  of  the  angle  of 
phase  represented  by  the  lagging  of  the  ampere  behind  the  volt  wave. 
Impedance. — Inductance  must  be  overcome  by  increased  electro- 
motive force, — that  is,  whereas  the  normal  expression  for  "C"  is  E  -f-  R, 
E  being  the  impressed  voltage  and  R  the  resistance  of  the  circuit,  in  the 
presence  of  inductance  C  becomes,  as  illustrated  in  Fig.  131, 


C  =  E^'R2  +  C'L, 

in  which  L  is  a  coefficient  of  self-induction.  E  of  this  value  is  the 
impedance,  the  impressed  voltage  or  the  ratio  of  produced  volts  to 
amperes.  When  there  is  no  induction,  that  is  in  steady  currents, 
impedance  equals  resistance. 

Capacity,  Reactance. — The  opposite  effect  of  inductance  occurs  in  a 
current  when  charging  a  condenser;  this  causes  the  amperes  to  lead  the 
volt  phase,  which  condition  is  termed  capacity,  being  caused  by  reactance 
of  the  condenser. 

Inductance  and  capacity,  being  opposite  in  effect,  may  be  created 
for  the  purpose  of  counteracting  each  other,  when  the  current  is  said  to 
be  non-inductive,  and  in  that  event  C  =  E  -f-  R. 

Watt-less  Current. — When  the  phase  of  volts  and  current  differs 
considerably  by  reason  of  lag  or  lead  caused  by  self-induction  or  capacity, 
the  actual  watt  output  is  less  than  what  would  be  indicated  by  the  prod- 
uct E  X  C.  Fig.  131  shows  the  two  components,  and  these  may  be 
considered  as  representative  of  the  working  and  the  watt-less  magnitudes. 

Continuous  Current;  Commutator. — The  alternate  current  (Fig.  132) 
may  be  made  continuous  in  direction  by  connecting  the  terminals  of  the 
conductor  to  separate  segments  of  a  ring,  the  segments  being  insulated 
from  each  other,  and  by  passing  metallic  brushes  over  the  circular  seg- 
ment surfaces  in  such  a  manner  that  the  gap  between  the  two  segments 
is  closed  by  the  brush  contact  at  the  period  when  the  alternation  of  the 
current  reversal  takes  place ;  the  exterior  circuit  is  connected  to  the 
brushes  and  the  commuted  current  flows  into  it  in  continuous  direction. 


EQUIPMENT 


337 


Figure    131 


H.E.P. 
H.  v.  S. 


213 


The  apparatus  through  which  the  alternate  current  is  changed  into  con- 
tinuous current  is  called  the  commutator. 

ARTICLE  95.  Dynamo  Parts;  their  Purpose  and  Design.  —  Electric 
dynamos  serve  the  purpose  of  generating  electric  energy,  the  origin  of 
which  may  be  continuous  or  alternating  current;  electric  energy  may 
therefore  be  generated  by  continuous  or 
alternating  current  dynamos  commonly 
called  D.  C.  generators  and  alternators. 
Any  dynamo  consists  in  general  of  the 
same  parts,  —  the  magnets,  which  are 
assembled  in  the  field,  and  the  conduc- 
tors, which  are  grouped  in  an  armature; 
one  of  these  parts  revolves,  and  then  is 
the  interior,  the  other  is  fixed,  and  is 
the  exterior;  both  are  concentric  of  each 
other.  The  fixed  or  exterior  part  becomes  'also  the  frame  of  the  machine, 
terminating  below  in  a  base  and  frequently  having  connected  to  it  shaft- 
bearing  stands;  the  interior  or  revolving  part  is  connected  to  the  shaft. 
The  variations  of  types  and  forms  of  parts  are  manifold,  and  it  is  not 
the  purpose  here  to  describe  any  particular  make,  but  to  give  such  an 

outline  of  the  purpose  and  theoretical 
design  of  the  principal  parts  as  to  enable 
the  investigator  to  recognize  compliance 
with  or  any  gross  departure  from  these 
essentials. 

Continuous-Current  Dynamos.  —  The 
field  consists  of  the  magnets  and  their 
windings.  The  magnets  are  radial  arms 
or  shoes  connected  to  a  yoke;  the  ex- 
treme ends  of  the  magnet  shoes  are 
the  poles. 

In  dynamos  of  large  output,  such  as  are  employed  in  the  equipment 
of  hydro-electric  plants,  the  field  is  multipolar,  as  distinguished  from  that 
of  small  continuous-current  dynamos,  in  which  the  field  consists  of  one 
magnet  or  two  poles,  being  termed  bipolar;  the  multipolar  dynamos 
have  four,  six,  eight,  or  more  poles  arranged  along  the  interior  periphery 
of  the  fixed  field,  the  frame  part  becoming  the  yoke,  or  to  the  exterior 

periphery  of  the  rotating  field  in  which  the  hub  represents  the  yoke. 
22 


figure    132 


214 


338  HYDRO-ELECTRIC    PRACTICE 

Magnet  arms  are  generally  built  up  of  laminated  (insulated)  metal  disks 
of  wrought  iron  or  mild  steel,  being  of  circular  or  other  shape.  The 
field  of  all  large  dynamos  consists  of  electro-magnets, — that  is,  the 
magnetization  is  created  by  passing  an  electric  current  through  con- 
ductors wound  around  the  magnet  limbs;  this  is  called  excitation  of  the 
field.  The  field  of  a  continuous-current  dynamo  is  self-excited;  the 
electric  current,  in  other  words,  carried  by  the  field  conductors  is  gen- 
erated in  the  dynamo  armature;  this  is  not  the  case  in  alternators,  as 
will  be  seen  later  on.  The  field  winding  may  be  of  the  continued  armature 
conductors,  which  is  called  series  wound;  or  it  may  be  of  a  smaller  con- 
ductor than  the  armature  coils  and  connected  with  the  armature  winding 
as  a  sort  of  splice;  this  is  called  the  shunt-wound  field;  and  finally  the 
field  winding  may  consist  of  a  combination  of  the  series  and  shunt  method, 
the  latter  overlying  the  former,  and  this  is  called  a  compound  wound 
field.  As  will  be  seen  later,  the  field  excitation,  and  therefore  its  winding, 
forms  one  of  the  most  important  means  of  regulation  of  the  output,  and 
therefore  this  characteristic  of  the  field  winding  practically  conveys,  in 
a  large  sense,  a  conception  of  the  efficiency  of  the  dynamo  as  to  the 
regularity  of  its  output.  There  are  many  reasons  for  the  desirability  of 
the  compound  winding  of  the  field,  and  it  is  practically  the  general 
practice  with  dynamos  of  large  output. 

The  section  of  the  magnets  and  the  amount  of  the  winding  depend 
upon  the  permeability  of  the  material  of  which  the  magnet  is  formed 
and  the  required  magnetization  of  the  field,  that  is  of  the  flux  density 
as  expressed  by  "N"  in  the  formula  of  electro-motive  force,  E  =  n  Z  N 

+  108. 

The  winding  is  measured  by  ampere-turns,  which  represent  the 
product  of  the  current,  in  amperes,  carried  by  the  wire  and  the  number 
of  turns  around  the  magnet  limb. 

The  permeability  of  magnets  of  wrought  iron  and  cast  iron  is  given 
in  the  following  table,  which  is  according  to  Prof.  Sylvan  B.  Thompson, 

where 

H  is  magnetic  force,  or  the  number  of  lines  per  square  inch  of  the 

field; 
B  is  the  flux  density,  the  number  of  lines  per  square  inch  of  the 

magnet  section;  and 
u  is  the  magnetic  permeability,   or  the  specific  conductivity,  for 

magnetic  lines,  of  the  material  in  the  magnet. 


EQUIPMENT 


339 


TABLE  30. 


WROUGHT  IRON. 
H 


30,000 

10.2 

2926 

40,000 

14 

2857 

50,000 

20.9 

2392 

60,000 

27.7 

2166 

70,000 

40 

1750 

80,000 

63 

1368 

90,000 

105 

856 

100,000 

245 

407 

110,000 

686 

161 

120,000 

1850 

64 

130,000 

4500 

28 

140,000 

7630 

18 

CAST  IRON. 

B 

H 

u 

25,000 

30 

843 

30,000 

53.5 

445 

40,000 

163 

245 

50,000 

447 

112 

60,000 

940 

64 

70,000 

1750 

40 

The  required  ampere  turns  for  the  field  winding  are  obtained  from 
different  formulas;  the  result  of  the  following  equation,  while  not  exact, 
will  give  practical  useful  values: 

S  C  =  (B  X  L  -f-  2.02)  X  1.25,  where 

S  C  are  ampere  turns  (current  in  spirals) , 

L  is  the  length  of  the  air  gap  in  inches,  and 

2.02  is  the  number  of  ampere  turns  required  to  produce  unit  flux 

density  in  an  air  space  one  inch  long, 
1.25  is  a  coefficient  to  compensate  for  the  drop  of  magnetic  potential. 

It  may  also  be  stated,  as  a  general  excitation  rule,  that  dynamos 
up  to  200  kilowatts  output  require  exciting  currents  of  0.05  to  0.025  of 
their  ampere  output,  and  of  1000  kilowatts,  0.015  and  less. 

The  magnet  section  may  be  determined  from  N  -=-  B;  N  is  the  total 
number  of  lines  of  force  and  B  the  flux  density  as  per  Table  30.  It  is 
common  practice  to  make  the  magnet  section  1.66  of  the  armature  core 
of  ring  and  1.25  of  drum  type. 

The  size  of  the  field  magnet  conductor  is  determined  from  the  ampere 
turns,  available  winding  space,  and  considerations  of  the  conductor's 
resistance;  the  usually  adopted  density  of  field-coil  current  is  limited 
to  2000  amperes  per  square  inch.  A  convenient  formula  for  the  finding 
of  field  coil  wire  is 

S  C  =  e  -f-  r,  where 

S  C  is  ampere  turns ; 

e,  the  voltage  at  the  terminals  of  the  field  coils;  and 

r,  the  resistance  of  one  turn  of  the  wire. 


340  HYDRO-ELECTRIC    PRACTICE 

Resistance  in  copper  wire  is  as  per  the  following  table. 


TABLE  31.—  TABLE  OF  COPPER  WIRE,  SIZE,  DIM] 

Gauge  B.  &  S. 
Brown 
& 

Sharpe                                                                         Mils  ilium. 

0000  460 

3NSION,  WE 

Circular  mils 
c.m.  =  d2. 

211,600 
167,800 
133,100 
105,600 
83,690 
66,370 
52,630 
41,740 
33,100 
26,250 
20,736 
16,384 
12,966 
10,404 
8,281 
6,561 
5,184 
4,096 
3.249 

IGHT,  AND  RESISTANCE. 

Weight  in 
Ibs.  per 
Resistance  in       1000  feet 
ohms  per  M  ft.         bare. 

0.04904             640 
0.06184             508 
0.07797            403 
0.09827             320 
0.12398             253 
0.15633             201 
0.19714             159 
0.24858             126 
0.31346             121 
0.39528              99 
0.491                   63 
0.6214                 50 
0.7834                 39 
0.9785                32 
1.229                   25 
1.552                   20 
1.964                   15.7 
2.485                   12.4 
3.133                     9.8 

000  410 

00  365 

0  325 

1  289 

2        .     258 

3  229 

4  204 

5  182 

6  162 

7  144.3 

8  128.5 

9  114.4 

10  101.9 

11  90.74 

12  80.81 

13  71.96 

14  64.08 

15.  .  .                                                                57.07 

Wire  Formulas.— c.m.  is  circular  mils;  R  is  resistance;  W  is  weight; 
L  is  length. 

R  =  11  X  L  -T-  c.m.;  c.m.  =  11  X  L  -f-  R;  W  =  L2  -r-  30,000  R; 
L  =  c.m.  X  R  -  11;  R  =  L2  -5-  30,000  W;  c.m.  =  1,000,000  W  •*•  3.03  L; 
L  =  W  X  R  X  30,000. 

The  armature  consists  of  the  core  and  the  conductor.  The  cores 
may  be  of  the  ring  or  drum  shape;  they  are  built  up  of  laminated  sheet 
iron  or  steel  disks,  commonly  from  25  to  50  mils  in  thickness,  the  ratio 
of  external  to  internal  diameter  of  ring  disks  being  5:3.  Drum  armature 
cores  are  generally  greater  in  diameter  than  they  are  long.  The  exterior 
disk  perimeter  is  shaped  for  the  convenient  and  safe  placing  of  the  con- 
ductors, the  forms  for  conductor  seats,  or  beds,  being  generally  of  the 
tooth  or  slot  type;  sometimes  they  are  circular  holes  near  the  exterior 
periphery. 

The  armature  winding  consists  usually  of  closed  rectangular  copper 
bar  coils;  the  schemes  of  windings  are  of  many  different  kinds, — parallel, 
series,  or  mixed  groupings, — and  in  either  of  them  the  winding  may  be 


EQUIPMENT  341 

of  lap  or  wave.  The  number  of  armature  conductors  is  ascertained  from 
Z  in  E  =  n  Z  N  -r-  108 ;  E  is  the  sum  of  the  volts  required  for  the  exterior 
circuit  and  those  lost  in  the  armature ;  the  latter  are  expressed  by  ra  Ca, 
where  ra  is  the  armature  resistance  and  Ca  the  armature  current.  The 
size  of  the  armature  conductors  is  found  from  the  wire  table,  the  practice 
being  to  allow  a  current  density  of  3000  to  4000  amperes  per  square  inch 
of  conductor.  The  core  section  is  found  from  the  determination  of  the 
winding  and  size  of  the  conductors. 

The  commutator,  sometimes  called  the  collector,  consists  of  bars  and 
brushes.  The  commutator  bars  are  usually  of  copper  drop  forgings  and 
of  a  length  equal  to  1.2  inches  per  100  amperes;  their  number  is  pro- 
portionate to  that  of  the  number  of  armature  coils.  Armature  brushes 
are  of  woven  copper  wire  gauze,  or  of  spring  copper  strips,  or  they  may 
be  of  carbons,  but  the  use  of  the  latter  requires  longer  commutator  bars. 
Mica  is  most  generally  used  for  the  insulation  of  the  commutator  bars 
from  the  armature  hub  and  from  each  other.  Brush  holders  are  the 
device  by  which  commutator  brushes  are  maintained  in  position;  they 
are  of  various  designs. 

Alternators  for  large  output,  as  required  for  the  equipment  of  hydro- 
electric plants,  are  generally  polyphase,  of  25  to  60  cycles  and  of  high 
voltage;  owing  to  the  greater  economy  and  safety  with  which  insulation 
for  high  voltage  can  be  secured  in  a  stationary  rather  than  a  moving 
mechanism,  the  high-voltage  alternators  for  transmission  service  are  of 
the  revolving-field  type,  the  armature  being  the  stationary  or  fixed  part. 

The  field  is  of  the  drum  type,  the  magnet  yoke  being  the  hub  and 
core,  the  limbs  are  secured  to  it  radially;  the  poles  are  more  numerous 
than  in  the  continuous-current  dynamo.  The  magnets  are  of  like  material 
and  construction  as  described  for  the  D.  C.  generators,  but  the  flux 
density  of  the  magnets  is  taken  at  a  considerably  lower  constant,  approx- 
imately 42,000. 

Excitation  is  not  practicable  by  the  alternating  current,  and  there- 
fore is  generally  provided  from  a  separate  continuous-current  dynamo; 
a  larger  inductive  drop,  due  to  the  choking  in  armature  coils  and  the 
demagnetization  effect  of  the  armature  current,  must  be  allowed  than 
in  the  D.  C.  dynamo  in  determining  the  ampere  turns  of  the  field  winding 
which  is  always  compounded. 

The  relation  of  speed,  number  of  poles  and  of  frequency  has  already 
been  noted;  it  is  expressed  by  n  =  0.5  p  X  (N  -r-  60),  where  n  is  the 


342  HYDRO-ELECTRIC   PRACTICE 

frequency  of  alternations,  the  cycles  or  periodicity,  p  is  the  number  of 
poles  (not  of  magnets),  and  N  the  revolutions  per  minute,  which  is  the 
usual  measure  of  speed. 

The  armature  of  the  revolving-field  alternator  is  a  cast-iron  ring 
into  which  the  laminated  armature  disks  are  dovetailed  along  the  interior 
periphery;  armature  disks  are  somewhat  thinner  than  those  used  in 
continuous-current  dynamo  armatures  because  of  the  higher  voltage, 
usually  from  0.012  to  0.008  inch.  The  armature  winding  is  determined 
in  like  manner  as  that  for  D.  C.  generators,  with  proper  consideration  of 
the  difference  between  the  impressed  and  the  actual  volts  which  was 
presented  in  Article  94;  the  lap  winding  is  preferable  for  high  voltage. 

ARTICLE  96.  Current  Reorganization. — The  generated  current  is,  as 
has  been  shown  in  Article  94,  continuous  or  alternating,  and  the  latter 
is  monophase  or  polyphase;  to  change  the  generated  current  into  any 
other  kind  of  current,  for  the  purpose  of  service,  is  characterized  as 
reorganization  of  the  current. 

The  generated  continuous  current  may  be  changed  to  alternate 
current  by  the  aid  of  a  motor-generator,  being  a  composite  machine  con- 
sisting of  a  motor  supplied  and  operated  by  the  generated  continuous 
current,  which  in  turn  operates  an  alternator  connected  to  it,  its  output 
being  alternating  current  of  mono-  or  polyphase.  The  generated  alter- 
nating current  may  be  rectified  into  continuous  current  by  means  of  the 
same  device,  in  which  case  the  motor,  of  the  induction  type,  is  supplied 
with  and  operated  by  the  generated  alternating  current  and  itself  operates 
the  continuous-current  dynamo. 

The  same  result  may  be  obtained  through  the  agency  of  a  rotary 
convertor,  and  by  a  shorter  process,  this  machine  being  a  continuous- 
current  dynamo  fitted  with  collecting  rings  in  addition  to  the  commutator. 
The  alternate  current  passes  by  way  of  these  rings  into  the  armature 
coils  and  thence  through  the  rotary  and  its  commutator,  and  therefore 
issues  as  continuous  current.  The  general  design  of  these  reorganizing 
machines  is  similar  to  that  of  generators,  as  presented  in  Article  95. 

The  phase  of  the  current  may  be  changed  from  mono-  to  polyphase, 
and  vice  versa,  by  the  aid  of  a  phase  transformer,  being  of  the  type  of  a 
motor  generator,  in  which  the  phase  reorganization  is  brought  about  by 
the  addition  to  the  commutator  of  slip  rings  and  by  their  appropriate 
connection  to  the  armature  conductors. 


EQUIPMENT 


343 


Fig.    133 


ARTICLE  97.  Current  Transformation. — When  the  voltage  (E.  M.  F.) 
of  any  current  is  raised  or  lowered,  it  is  said  to  be  transformed.  As  may 
be  inferred  from  the  origin  and  characteristics  of  continuous  current,  as 
briefly  presented  in  Article  94,  this  type  of  current  can  be  transformed 
only  by  means  of  moving  apparatus. 

Continuous-current  dynamos  may  be  connected  in  series,  in  which 
case  the  voltage  in  the  exterior  circuit  is  the  aggregate  of  the  voltages 
of  the  D.  C.  dynamos  thus  connected;  the  only  other  process  of  trans- 
forming continuous  current  is  by  the  agency  of  the  motor  generator 
mentioned  in  the  previous  article. 

Alternating-current  voltage  may  be 
raised  or  lowered  by  the  aid  of  static 
transformers,  in  accordance  with  the  fol- 
lowing theory.  It  has  been  noted  in 
Article  93  that  when  a  conductor  carry- 
ing current  is  passed  around  a  closed 
magnetizable  core,  magneto-electric  force 
is  set  up  in  the  core;  when  the  current 
in  the  coil  is  of  the  alternating  kind,  the 
induced  magnetic  force  retains  the  char- 
acteristics of  alternations  both  in  direc- 
tion and  flux  density,  and  by  virtue  of 
this  condition  magnetic  stress  is  set  up 
which  becomes  the  source  of  an  electro- 
motive force  other  than  that  of  the  current  in  the  circuit  which  passes 
around  the  core.  This  induced  electro-motive  force  acts  in  opposition  to 
that  of  the  magnetizing  circuit  and  thus  incites  the  latter  to  increased 
activity.  If  another  conductor  circuit  is  passed  around  the  same  core 
and  is  not  connected  with  the  magnetizing  circuit,  the  increase  of  E. 
M.  F.  in  the  latter  finds  an  outlet,  or  overflow  so  to  speak,  into  this 
other  conductor,  and,  under  the  constant  pressure  from  its  source,  and 
the  continued  conflict  between  it  and  the  back  E.  M.  F.  due  to  the 
magnetic  stress  set  up  in  the  core,  it  continues  to  pass  into  the  second 
conductor. 

This  is  the  principle  of  alternating  current  transformation  illustrated 
by  Fig.  133,  in  which  C  is  the  core  above  mentioned,  P  is  the  magnetizing 
circuit  called  the  primary,  and  S  is  the  second  circuit,  being  the  secondary. 


H.E.P. 
H.v.  S. 


210 


344  HYDRO-ELECTRIC   PRACTICE 

It  may  be  pointed  out  that  this  current  phenomenon  may  be  likened  to 
what  transpires  in  the  operation  of  a  generator,  that  the  primary  is  like 
the  field  and  the  secondary  the  armature,  while  mechanical  motion  is 
represented  by  the  alternations,  that  is  the  continuous  coming  and  going 
of  flux  density  and  direction,  which  is  practically  of  the  same  effect,  as 
far  as  cutting  of  magnetic  lines  in  a  space  of  time  is  concerned,  as  when 
the  armature  revolves  and  passes  through  the  field  in  that  manner; 
and  from  this  it  will  at  once  be  clear  that  no  such  phenomenon  can  occur 
with  continuous  current  that,  though  the  core  would  be  magnetized, 
there  would  be  no  current  in  the  secondary. 

Static  Transformer  Analysis. — When  the  secondary  is  an  open  circuit, 
there  is  no  transformation  of  E.  M.  F. ;  the  magnetization  of  the  core 
originates  a  back  electro-motive  force  of  practically  the  same  value  as 
that  of  the  primary,  being  diminished  only  by  the  voltage  required  to 
overcome  the  resistance  of  the  primary  coil. 

When  the  secondary  is  closed,  a  current  is  set  up  in  it  opposing  that 
in  the  primary,  its  first  effort  being  to  demagnetize  the  core,  and,  since 
it  is  the  expressed  purpose  of  the  primary  to  magnetize  the  core,  a  conflict 
or  stress  is  set  up  which  calls  forth  greater  efforts  of  the  primary  to 
overcome  the  opposition  of  the  demagnetizing  influences,  with  the  result 
that  a  distinct  current  passes  into  the  secondary,  being  of  like  frequency 
and  other  characteristics  as  the  primary  excepting  as  to  the  E.  M.  F., 
as  it  is  the  purpose  of  the  process  to  alter  or  transform  this  by  raising  or 
lowering  the  voltage  of  the  primary  to  any  desired  in  the  secondary. 
The  E.  M.  F.  in  these  two  circuits  is  proportional  to  the  number  of  turns 
in  each  which  pass  around  the  core,  which  is  analogous  to  the  principle 
of  field  excitation  explained  in  Article  95.  In  Fig.  133  the  primary  is 
shown  of  one  turn  while  the  secondary  has  four  turns  around  the  core; 
the  .voltage  of  the  secondary  will  therefore  be  four  times  that  of  the 
primary,  while  the  current,  amperes,  in  the  secondary  will  be  one-fourth 
of  those  of  the  primary.  In  this  case  the  voltage  is  raised  by  a  step-up 
transformer,  the  lowering  of  the  voltage  would  be  secured  through  a 
step-down  transformer,  both  being  of  the  same  design  and  construction 
excepting  as  to  the  respective  winding  of  the  primary  and  secondary 
coils,  which  represents  the  ratio  of  transformation.  In  this  connection 
it  should  be  noted  that  with  like  current  density  per  conductor  section 
unit  (square  inch)  the  ratio  of  transformation  must  be  accompanied  by 


EQUIPMENT  345 

a  corresponding  adaptation  of  conductor  cross-section;  thus  the  con- 
ductor in  the  secondary  of  a  step-down  transformer  must  have  an 
increased  copper  section  over  that  of  the  primary  which  is  inversely  to 
the  voltage  drop. 

Static  transformers  consist  of  the  core,  the  windings,  and  the  shell. 
The  cores  are  of  many  different  shapes,  being  generally  formed  of  lami- 
nated iron  disks;  the  windings  are  of  insulated  copper  wire.  There  is 
no  particular  limit  to  the  transformation  ratio,  the  principal  consid- 
eration in  this  regard  being  the  heat  which,  is  generated  in  the  trans- 
former and  may  rise  to  a  degree  at  which  the  insulations  would  suffer 
destruction;  high- voltage  transformers  are  therefore  especially  designed 
to  keep  this  feature  well  insured  by  employing  different  methods  of 
cooling  the  transformer  and  its  various  parts.  Transformer  coils  are 
often  placed  in  oil,  which  receives  the  heat  and  transmits  it  to  the 
shell  where  it  is  readily  radiated;  the  oil  is  also  separately  cooled 
by  passing  water  through  pipe  coils  immersed  in  it;  again  cooling  is 
effected  by  passing  cold  air  through  the  transformers,  either  by  a  blower 
or  fan  system. 

The  losses  in  static  transformers  may  be  kept  very  low  by  proper 
design  and  construction;  they  are  due  to  the  resistance  of  the  sec- 
ondary coils,  to  magnetic  flux  friction  in  the  core,  and  to  idle  or  eddy 
currents  which  are  set  up  in  the  core;  the  aggregate  need  not  exceed 
2  per  cent. 

ARTICLE  98.  Current  Transmission. — Theory. — Electric  energy  may 
be  conducted  to  any  distance,  as  its  flow  will  always  continue  from  a 
high  to  a  lower  potential,  but,  as  in  transmission  of  energy  of  any  form, 
work  is  constantly  being  performed  during  its  passage  through  the  con- 
ductor, and,  at  some  point  or  other,  the  energy  thus  expended  may  be- 
come so  great  a  part  of  the  impressed  volume  that  its  transmission,  under 
such  conditions,  represents  a  waste  rather  than  a  gain. 

The  work  of  the  current  during  its  transmission  is  that  of  overcoming 
the  conductor's  resistance  to  its  free  passage;  just  as  the  flow  of  water 
through  a  pipe  is  impeded  by  the  roughness  of  the  pipe's  perimeter  or 
its  change  of  section,  which  is  overcome  by  the  expenditure  of  head,  so 
the  transmission  of  electric  energy  is  made  possible  only  by  the  over- 
coming of  the  conductor's  resistance,  which  is  accomplished  by  the 
expenditure  of  E.  M.  F.  By  Ohm's  law  C  =  E  --  R  and  E  =  C  R  and 


346  HYDRO-ELECTRIC   PRACTICE 

R  =  E  -r-  C,  from  which  R,  the  resistance  in  any  length  of  a  certain 
conductor,  may  be  ascertained  from  1  X  r  -=-  cm,  where 

1  is  the  length  of  the  conductor  in  feet; 

r  is  the  resistance  unit,  being  the  resistance  of  one  foot  of  copper 

wire  of  one  mil  section  (one  mil  foot),  which  =  10.8  ohms,  but 

is  taken  as  11  ohms,  whereby  the  irregularities  of  the  wire's 

section  and  the  faults  of  joints  are  compensated  for; 

cm  stands  for  the  area  of  the  conductor's  section  in  circular  mils; 

therefore 

R  =  11  X  1  -j-  cm,  and,  inserting  this  in  above  equation  for  R, 
R  =  E  -r-  C,  it  becomes  11  X  1  -r-  cm  =  E  -r-  C,  in  which 
C  is  the  current  (amperes)  which  is  to  be  delivered  for  service, 
E  is  the  electro-motive  force  to  be  expended  in  overcoming  the 
resistance  of  the  conductor,  being  termed  the  transmission  loss 
or  the  voltage  drop. 

Aluminum  wire  is  well  adapted  for  the  purpose  of  transmission 
conductors;  the  ohmic  resistance  coefficient  of  aluminum  is  17  per  mil 
foot  instead  of  11,  the  coefficient  for  copper,  and  this  value  must  be 
inserted  in  above  formula  when  aluminum  wire  is  being  investigated 
instead  of  copper  wire. 

Since,  from  above  formula,  the  resistance  may  be  found  for  any  size 
of  conductor,  so  may  the  size  be  determined  from  it  to  transmit  a  fixed 
current  at  a  given  line  voltage  over  a  known  distance ;  that  is,  from  above 

cm  =  1  X  11  X  C  H-  E  for  copper  and 
cm  =  1  X  17  X  C  -T-  E  for  aluminum. 

The  weight  of  1000  feet  of  1000  cm  copper  wire  is  approximately  3  Ibs. 
The  weight  of  1000  feet  of  1000  cm  aluminum  wire  is  approximately  1.5  Ibs. 
By  symbolizing  1000  feet  of  the  conductor's  length  as  L,  the  weight  of 
the  conductor  may  be  expressed  from  the  foregoing  formula  by 

W  =  L2X33      XC-^E  for  copper  conductors,  and 
W  =  L2  X  23.5  X  C  -*•  E  for  aluminum  conductors. 

This  refers  to  a  single  conductor. 


EQUIPMENT  347 

From  these  expressions  and  from  formerly  discussed  current  char- 
acteristics, it  is  apparent  that  E  is  the  principal  factor  controlling  the 
value  of  W,  for  instance  when  the  ratio  of  percentage  of  line  drop  from 
the  impressed  electro-motive  force  is  fixed,  the  doubling  of  the  impressed 
voltage  will  halve  C,  double  E,  and  reduce  W  to  one-fourth;  therefore, 
the  weight  of  the  transmission  conductor  for  given  length,  current,  and 
drop  varies  inversely  as  the  square  of  the  impressed  voltage,  and  for  given 
current  and  drop  and  impressed  voltage  in  direct  proportion  to  length 
of  transmission,  the  weight  remains  constant;  while  for  given  current  and 
drop  the  weight  increases  as  the  square  of  the  length. 

For  the  purpose  of  hydro-electric  practice  all  current  transmission 
factors  may  be  determined  from  these  formulae  with  sufficient  accuracy 
to  estimate  the  transmission  conductors  and  their  cost,  but  many  refine- 
ments enter  the  problem  when  considered  from  a  scientific  stand-point. 
Diagram  16,  appearing  in  connection  with  Article  28  in  Part  I.  of  this 
book,  has  been  calculated  for  copper  wire  from  above  formula  and  is 
correct,  within  its  scope,  for  the  purpose  of  estimating  the  wire  quantity. 

Transmission  of  continuous  and  of  single  and  two-phase  alternating 
currents  is  by  two  wires,  all  the  current  passing  over  every  part,  while 
three-phase  alternating  current  may  be  transmitted  by  three  conductors, 
each  of  which  carries  the  current  of  its  particular  phase.  In  the  above 
formulae,  for  determining  cm  or  W  of  transmission-line  conductors,  the 
length,  when  considering  continuous  and  single  and  two-phase  alternat- 
ing currents,  or  in  two-conductor  circuits,  is  the  developed  length  of  the 
conductors  or  double  the  transmission  distance,  while  for  three-phase 
alternating  current  transmission  the  length  is  equal  to  the  transmission 
distance.  In  finding  the  weight,  therefore,  L  is  multiplied  by  four  for 
two-conductor  lines  and  by  three  for  three-conductor  lines ;  for  this  reason 
a  three-conductor  transmission  line  (of  three-phase  current)  requires 
only  75  per  cent,  of  the  weight  of  copper  needed  in  a  two-conductor  line 
of  the  same  energy. 

Of  the  current  symptoms  briefly  outlined  in  Article  94  those  specially 
applying  to  current  transmission  are :  inductance,  which  is  the  absorption 
of  electric  energy  while  producing  a  magnetic  field  around  the  conductor, 
or  the  setting  up  of  an  electro-motive  force  opposite  to  that  impressed  in 
the  alternate  current  conductor,  resulting  in  voltage  drop  at  the  line 
terminal;  capacity,  being  the  reactance  of  the  transformation  of  alter- 


348  HYDRO-ELECTRIC   PRACTICE 

nating  current  and  resulting  in  an  increase  of  current  in  the  circuit;  and 
resonance,  which  is  the  neutralization  of  inductance  and  capacity  with 
the  effect  of  a  considerable  rise  in  the  line  voltage.  The  effects  of  all 
these  in  transmission  are  best  met  by  an  addition  of  not  less  than  five 
per  cent,  to  the  cm  or  W  of  the  transmission  conductor  as  found  from  the 
quoted  formulae. 

ARTICLE  99.  Current  Regulation. — This  subject,  like  the  preceding 
electrical  topics,  will  be  treated  herein  only  to  the  extent  of  presenting 
the  apparatus  and  the  purpose  which  it  serves,  as  it  may  have  to  be 
considered  in  connection  with  the  planning  of  the  hydro-electric  operat- 
ing plant  and  its  equipment  and  for  the  preparing  of  the  estimate  cover- 
ing these. 

Regulation  of  current  generating  is,  as  has  been  pointed  out  in 
Articles  94  and  95,  first  secured  by  the  turbine  governor  and  second 
by  field  excitation,  the  first  maintaining,  as  near  as  practicable,  constancy 
of  mechanical  speed,  the  second  of  electro-motive  force  or  pressure.  The 
former  is  practically  automatic,  but  the  latter  needs  more  or  less  personal 
attention,  depending  upon  the  current  reorganization  and  transforma- 
tion methods  and  means,  the  character  of  the  current  service,  and  the 
fluctuations  of  the  loads.  At  any  rate  certain  apparatus  is  required  to 
indicate  output  characteristics  and  detect  irregularities,  while  others 
are  needed  to  furnish  ready  correction  for  these. 

The  purpose  of  regulation  is  generally  to  maintain  constancy  of 
pressure,  voltage,  in  the  exterior  circuit,  which,  in  the  case  of  hydro- 
electric plant  output,  is  the  transmission  line.  At  the  generator,  as  has 
been  noted,  this  is  principally  accomplished  by  regulating  the  exciting 
current,  as  this  is  the  origin  of  the  electro-motive  force;  on  the  line, 
regulation  may  be  secured  through  static  transformers  with  alternating 
current.  Transformation  is  generally  effected  through  a  bank  of  trans- 
formers of  equal  units  connected  in  series,  but,  as  the  cause  of  the 
fluctuations  is  mainly  to  be  found  at  the  service  end  of  the  line,  regulation 
is  best  arranged  for  at  this  terminal,  the  substation. 

Regulating  apparatus  may  be  classified  into  switches,  testing  instru- 
ments, and  correctors,  most  of  which  are  collected  on  the  switchboard, 
which  consist  of  marble  or  slate  tablets  or  panels  placed  against  a  suitable 
frame  in  the  generating  room  and  in  the  substation.  The  circuit  con- 
ductors are  led  to  the  back  of  the  switchboard  panels,  the  latter  being 


EQUIPMENT  349 

perforated  at  the  places  where  the  switches  or  apparatus  are  to  be  secured 
so  that  they  can  be  connected  with  the  conductor  circuits. 

Switches,  or  circuit  breakers  and  closers,  are  devices  by  which  con- 
ductor circuits  are  closed  or  opened;  they  are  of  various  designs,  all 
aiming  to  make  or  break  the  current  by  avoiding  any  arcing  across.  High- 
voltage  switches  are  therefore  necessarily  of  special  designs  and  con- 
struction, and  wherever  practicable  the  switching  of  such  currents  is 
arranged  for  on  the  low-voltage  side  of  the  circuit.  Circuit  breakers  may 
be  of  air  or  oil  break  type,  the  latter  being  always  employed  in  high- 
voltage  practice,  and,  when  the  voltage  is  very  high,  20,000  and  more, 
oil  circuit  breakers  are  operated  by  secondary  pneumatic  or  electric 
power  devices  and  are  removed  from  the  vicinity  of  any  of  the  other 
electric  equipment. 

Testing  instruments  comprise  ammeters  (amperemeters),  which  are 
of  the  galvanometer  type,  indicating  the  current  strength  by  the  deflection 
of  a  magnetic  needle  placed  inside  or  over  a  coil  of  insulated  wire  through 
which  the  current  to  be  measured  is  passed.  Voltmeter  is  an  instrument 
similar  to  the  ammeter,  of  electro-magnetic  type,  its  purpose  being  to 
indicate  the  voltage  of  the  current. 

Wattmeter  is  the  third  of  this  class  of  testing  instruments,  indicating 
the  watts ;  though  voltage  and  amperes  are  indicative  of  the  watt  output 
of  the  continuous  current,  this  is  not  necessarily  the  case  with  the  alter- 
nating current,  where  the  product  of  the  volts  and  amps  represents  the 
apparent  watts,  while  the  wattmeter  indicates  the  effective  watts. 

Phasemeters  indicate  the  power  factor  of  the  current,  which  is  the 
ratio  of  effective  and  apparent  watts,  or  the  phase  difference.  Syn- 
chronizers or  phase  indicators,  as  their  name  implies,  indicate  when 
synchronism,  that  is  union  of  frequencies  in  the  alternating  current, 
exists  between  different  alternators  which  are  to  be  operated  in  parallel. 

Pilot  lamps  are  connected  across  the  dynamo  terminals  for  the 
ready  indication  of  the  approximate  pressure  by  the  degree  of  their 
incandescence. 

Ground  detectors  are  required  for  detecting  and  measuring  grounds 
and  leaks. 

Correctors  are  lightning  arresters,  which  may  be  placed  at  the  gen- 
erating plant,  along  the  transmission  line,  and  at  the  substation,  for  the 
purpose  of  diverting  lightning  charges.  There  are  various  types  of  these; 


350  HYDRO-ELECTRIC   PRACTICE 

one  in  common  use  consists  of  a  number  of  air  gaps  between  conductor 
plugs  set  in  a  porcelain  block.  Guard  wires  are  also  employed  for  light- 
ning diversion  from  transmission  lines;  they  are  metallic  circuits  (iron) 
grounded  at  intervals  of  1000  feet. 

Choking  coils  are  of  copper  wire  so  wound  on  or  around  iron  core 
pieces  as  to  possess  high  self-induction  when  used  on  alternating  cir- 
cuits; their  purpose  is  to  obstruct  or  cut  off  alternating  current  with  a 
smaller  loss  of  energy  than  if  it  were  used  as  ohmic  resistance. 

Booster  is  a  dynamo  connected  to  a  separate  circuit  for  the  purpose  of 
raising  its  voltage  above  that  of  the  other  system  of  which  it  forms  a  part. 

Rheostats  are  adjustable  resistance  coils. 

ARTICLE  100.  Electric  Generating  Plant. — The  character  of  the  gen- 
erating equipment  is  to  be  determined  with  a  view  of  securing  high 
efficiency  of  resourceful  output  at  reasonable  first  and  lowest  practicable 
maintenance,  depreciation,  and  operating  cost. 

The  matters  to  be  determined  are: 

(a)  the  kind  of  current  to  be  generated, 

(b)  the  generator  voltage, 

(c)  the  generator  units, 

(d)  the  mechanical  power  application  to  generators  and  exciters, 

(e)  the  types  of  generators,  exciters,  and  governors, 

(f)  the  arrangement  of  the  apparatus; 

the  controlling  features  in  this  quest  are: 

(g)  the  distance  to  the  current  market, 
(h)  the  character  of  the  current  service, 

(i)  the  available  hydraulic  and  mechanical  factors,  and 

(j)  the  output  efficiency,  time  delivery,  and  cost  of  apparatus. 

The  current  to  be  generated  must  be  determined  from  the  character 
of  the  current  service  and  from  the  market  distance.  Continuous  current 
is  largely  employed  for  arc  lighting,  exclusively  for  electrolithic  opera- 
tions and  accumulator  charging,  and  is  preferable,  at  the  present  state 
of  the  practice,  for  power  service  in  which  the  fluctuations  of  the  load  are 
sudden  and  excessive,  such  as  electric  traction  and  lifting.  The  alter- 
nating current  is  largely  used  for  incandescent  lighting  and  mechanical 


EQUIPMENT  351 

power  application  for  factory  and  shop  machinery  and  tools,  pumps  and 
elevators. 

The  influence  of  the  distance  to  the  market  is  most  potent  with  a 
transmission  system,  and,  as  far  as  it  has  a  bearing  upon  the  choice  of 
the  kind  of  current  to  be  generated,  it  is  largely  a  question  of  economics. 
The  principal  items  in  the  cost  of  the  transmission  plant  are  the  con- 
ductors, and  the  weight  of  these,  as  has  been  noted,  with  fixed  output, 
distance  and  line  drop,  depends  entirely  upon  the  impressed  or  generat- 
ing voltage.  The  voltage  of  continuous-current  generators  is  limited, 
by  reason  of  the  commutator  device,  to  approximately  2000  volts;  if 
several  D.  C.  generators  are  connected  in  series  the  voltage  sent  into  the 
exterior  circuit  will  be  the  aggregate  of  all  the  generators  thus  connected. 
Alternators  may  be  designed  to  generate  at  high  voltages,  200,000 
being  now  altogether  practicable.  Transformation  of  continuous-current 
voltage  is  practicable  only  by  the  aid  of  motor  generators,  while  that  of 
alternating  current  is  accomplished  through  static  transformers.  All 
these  limitations  of  the  continuous  current  point  to  the  alternating  cur- 
rent as  preferable  when  transmission  to  a  considerable  distance  is  required, 
even  though  the  service  calls  for  continuous  current  only. 

Example  1. — An  electrolithic  plant  is  to  be  furnished  1000  kilowatts 
of  continuous  current  at  a  voltage  of  250  from  a  hydro-electric  power 
plant  one  mile  distant;  the  drop  or  loss  of  pressure  in  transmission  is 
to  be  kept  within  5  per  cent.  If  continuous  current  is  generated  at  a 
voltage  of  275  and  transmitted  at  this  voltage  to  the  electrolithic  plant, 
the  generating  plant  will  consist  of  one  or  two  D.  C.  generators  and  the 
transmission  line;  the  conductors  for  the  latter  are  two  strands  of  wire 
of  aggregate  weight  found  from  W  =  4  L2  X  33  X  C  -f-  E. 

L  is  in  1000  feet  units,  the  length  of  a  transmission  mile  of  con- 
ductors being  taken  at  5400  feet  to  compensate  for  the  sag 
between  supports; 

C  is  the  current  in  amperes  to  be  delivered  at  the  electrolithic  plant, 
being  =  1,000,000  +  250  =  4000; 

E  is  the  line  voltage  drop  =  275  X  0.05  =  14;  therefore 

W  =  156.64  X  33  X  4000  -*-  14  =  1,470,857  Ibs. 

If  alternating  current  is  generated  at  2300  volts,  which  is  a  standard 
type  alternator,  and  transmitted  at  this  voltage  to  the  customer  in  ques- 


352  HYDRO-ELECTRIC   PRACTICE 

tion,  one  mile  distant,  with  a  line  drop  of  5  per  cent.,  the  generating  plant 
will  consist  of  one  or  two  alternators,  the  transmission  line,  and  a  rotary 
converter  by  which  the  current  is  reorganized  to  the  required  continuous 
current.  The  conductors  for  this  line  will  consist  of  three  strands  of  wire, 
the  current  being  of  the  three-phase  type,  and  the  weight  of  the  line  wire 
is  found  from  W  =  3  X  L2  X  33  X  C  -*-  E,  in  which 

C  =  1,000,000  -r  2185  and  E  =  2300  X  0.05;  therefore 

W  =  3  X  29.16  X  458  +  115  =  11,500   Ibs.,    to   which   should   be 

added  for  induction  5  per  cent.,  making  the  total  weight  = 

12,075  Ibs. 

The  alternator  may  generate  at  a  higher  voltage  without  the  neces- 
sity of  raising  the  line  voltage,  and  thus  the  weight  of  the  required  con- 
ductors may  be  still  further  reduced;  however,  it  is  clear  that  this  plant 
should  generate  alternating  current. 

Example  2. — An  electric  power  crane  unloading  iron  ore  and  fuel 
from  vessels  is  to  be  supplied  with  500  kilowatts  of  continuous  current 
at  a  voltage  of  400  from  a  hydro-electric  power  plant  half  a  mile  distant. 
For  continuous  current  the  generating  plant  would  consist  of  one  D.  C. 
generator  and  the  transmission  line,  and  the  weight  of  the  required  con- 
ductors is  again  found  from 

W  =  4  X  2.600*  X  33  X  1259  -*-  20  =  55,688  Ibs. 

If  alternating  current  is  generated  for  this  service,  the  plant  will  consist 
of  the  alternator,  the  line,  and  a  rotary  converter;  the  current  may  be 
generated  at  a  voltage  of  2300  and  thus  transmitted  without  step-up 
transformers  being  added;  the  line  would  consist  of  three  strands  of 
wire  and  the  weight  from 

W  =  3  X  2.600*  X  33  X  234  *  115  =  1364  Ibs., 

to  which  should  be  added  5  per  cent.,  making  the  total  conductor  weight 
approximately  1432  Ibs.,  being  54,256  Ibs.  less  than  required  for  the 
continuous-current  line.  The  question  to  be  decided  is,  the  comparative 
cost  of  this  quantity  of  conductor  and  that  of  the  rotary,  to  which  the 
operating  and  maintenance  cost  of  the  rotary  may  have  to  be  added 


EQUIPMENT  353 

unless  the  customer  will  take  over  its  operation.  From  this  it  appears 
that  the  distance  limit  at  which  continuous-current  generation,  for 
continuous-current  service  taking  up  the  entire  output,  is  to  be  preferred 
to  alternating-current  generating  and  current  reorganization,  lies  inside 
of  the  one  mile  for  outputs  of  less  than  1000  kilowatts,  and  that  for 
greater  distances  or  larger  outputs  the  alternating  current  proves  the 
more  economical  for  the  generating  plant. 

With  the  current  decided,  the  next  question  is  as  to  the  phase  and 
the  frequency.  A  great  deal  might  be  said  on  this  topic  as  having  a  bear- 
ing one  way  or  the  other,  but,  after  all,  the  safest  guide  may  be  found  in 
practice,  which,  in  this  country  at  least,  at  present  is  largely  in  favor 
of  the  three-phase  current  at  the  generating  end.  The  important  influence 
of  phase  characteristic  on  the  transmission-line  conductor  has  already 
been  noted  and  distinctly  points  to  the  preference  of  the  three-phase 
current. 

The  question  of  frequency  is  not  so  positively  settled,  as  it  depends 
largely  upon  the  character  of  the  current  service.  When  the  bulk  of  the 
current  is  intended  for  power  service,  the  lower  frequency  of  25  cycles 
lays  claim  to  several  advantages  over  a  higher  one.  The  cost  of  rotary 
converters  rises  with  the  frequency,  as  it  requires  more  poles  and  more 
costly  armature  construction  than  for  low  frequencies;  on  the  other 
hand,  the  cost  and  weight  of  static  transformers  is  greater  for  low  than 
for  higher  frequencies,  and  therefore  as  far  as  the  cost  item  is  concerned 
the  most  economical  mean  between  transformers  and  reorganizers  should 
readily  offer  the  solution.  When  the  service  load  is  fairly  distributed 
between  lighting  and  power  production,  the  60-cycle  current  appears  to 
be  preferable  over  that  of  lower  frequencies. 

The  next  current  characteristic  to  be  decided  is  the  generator  voltage, 
and  for  transmission  duty  there  is  little  doubt  that  every  desideratum 
points  to  the  highest  practicable.  Alternators  of  high  voltage  should 
be  less  costly  than  low-voltage  generators  plus  step-up  transformers, 
though  their  depreciation  and  maintenance  may  be  somewhat  greater. 
However,  the  factor  of  transformer  loss,  which  with  high-generator 
voltage  may  be  avoided,  carries 'considerable  weight  in  the  summing  up. 
For  transmission  distances  up  to  ten  miles  it  will  generally  be  found 
more  economical  to  generate  at  a  sufficiently  high  voltage  to  make  step- 
up  transformers  unnecessary,  and  this  distance  may  even  be  doubled  if 
the  alternator  voltage  comes  up  correspondingly.  ^ 

23 


354  HYDRO-ELECTRIC    PRACTICE 

Generator  units  are  more  largely  to  be  determined  by  the  hydraulic 
conditions  than  any  other  factor.  It  will  now  be  fully  realized  that  high 
generator  speed  is  much  to  be  desired,  and  if  the  drive  is  to  be  by  direct 
coupling  to  the  turbine  shaft  the  choice  of  the  generator  unit  will  generally 
not  be  doubtful.  As  a  rule,  it  is  advisable  to  have  duplicate  units  of  like 
capacity  to  meet  unforeseen  emergencies  by  which  any  of  them  may  be 
put  temporarily  out  of  commission,  and,  with  this  important  proviso 
and  the  desideratum  of  high  speed,  the  units  are  preferably  of  the  largest 
practicable  output,  that  is  within  the  limits  of  economical  standard 
designs. 

This  leads  to  the  fourth  point  to  be  determined  in  connection  with 
the  composition  and  character  of  the  generating  equipment,  the  mechanical 
power  application  for  generators  and  exciters.  There  exists  at  the  present 
day  a  certain  almost  hysterical  clamor  for  direct-connected  apparatus; 
ostensibly  it  is  influenced  by  the  desire  to  make  the  greatest  showing  of 
economical  energy  utilization,  to  avoid  the  loss  due  to  other  than  direct 
drives,  while  frequently  the  stickling  for  this  arrangement  results  in  far 
greater  energy  waste,  because  the  most  suitable  generating  equipment 
is  barred  out,  and  in  this  manner  a  rational  study  and  analysis  of  the 
opportunity  is  overshadowed  by  the  desire  to  have  things  "up  to  date," 
at  least  as  far  as  appearances  go.  There  are  quite  a  number  of  the  present 
important  hydro-electric  plants  which  might  have  been  bettered  by 
several  per  cent,  of  output  if  equipment  were  belt  driven  instead  of  being 
direct  connected.  At  any  rate  direct-connected  apparatus  may  not  always 
be  the  most  economical  (or,  rather,  efficient)  solution  of  this  problem. 
Speed  lies  at  the  root  of  it  all,  and  by  this  the  size,  voltage,  and  cost  of 
apparatus  are  fixed;  a  balancing  of  the  value  of  the  lost  energy  through 
belt  drive,  as  compared  with  direct  connection,  against  the  difference  in 
cost  of  the  generating  and  transmission  plant  which  is  required  for  either 
programme,  will,  as  a  rule,  plainly  point  to  the  one  to  be  preferred.  There 
is  much  less  to  be  said  in  favor  of  gear-driven  equipment,  which,  how- 
ever, comes  under  consideration  with  low-head  developments  and  may 
then  be  the  only  solution  of  this  question  of  mechanical  power  application. 

Exciters  are  preferably  driven  by  separate  turbine  units.  The  type 
of  the  generator  equipment  should  generally  be  decided  in  favor  of  that 
offered  by  the  lowest  competitive  tender  who  guarantees  prompt  delivery 
of  the  specified  apparatus.  All  of  the  leading  American  manufacturers 
of  electric  dynamos  produce  equally  reliable  and  efficient  machines,  and, 


EQUIPMENT 


355 


when  the  desired  characteristics  and  output  efficiencies  are  clearly 
specified,  as  will  be  outlined  in  the  last  chapter  dealing  with  specifica- 
tions, this  question  should  be  satisfactorily  solved  by  adopting  approved 
business  methods. 

The  arrangement  of  the  equipment  in  the  power  station  must  be  made 
with  ample  allowance  of  operating  space  around  every  machine  and 
accessory  apparatus,  good  light  should  be  available  for  switchboards, 
and  the  station  should  be  planned  not  merely  to  hold  the  outfit  but  also 
to  move  it  about,  in  and  out,  without  interfering  with  operations,  and, 
finally,  possible  additions  must  be  taken  into  consideration,  as  a  paying 
plant  is  also  a  growing  one.  Diagram  40  gives  the  approximate  dimen- 
sions of  alternators  of  different  output  and  speeds  at  2300  volts,  which 
is  standard  and  well  adapted  to  most  conditions. 

The  following  table  gives  a  list  of  generators,  their  capacity  and 
speed,  which  are  of  standard  types  with  American  manufacturers,  and 
can  therefore  be  obtained  within  reasonable  delivery  periods  and  on 
competitive  tenders. 

TABLE  32.— STANDARD  GENERATORS,  ALTERNATORS,  2  AND  3  PHASE,  2300  VOLTS 

AND  UP. 


Drive. 

K.W. 

Frequency. 

Pole; 

Coupled.  .  .  . 

..      100 

69 

24 

Coupled.  .  .  . 

..      100 

60 

8 

Coupled  .... 

.  .      105 

60 

28 

Coupled.  .  .  . 

..      110 

30 

6 

Coupled.  .  .  . 

..      115 

60 

8 

Coupled.  .  .  . 

.  .      125 

60 

32 

Coupled.  .  .  . 

.  .      125 

60 

26 

Coupled.  .  .  . 

..      120 

25 

6 

Coupled.  .  .  . 

.  .      120 

25 

4 

Coupled.  .  .  . 

.  .      150 

60 

32 

Coupled.  .  .  . 

.  .      150 

60 

26 

Coupled.  .  .  . 

.  .      150 

60 

20 

Coupled.  .  .  . 

..      150 

60 

14 

Coupled.  .  .  . 

.  .      150 

60 

12 

Coupled  .... 

.  .      150 

60 

8 

Coupled.  .  .  . 

.  .      175 

60 

36 

Coupled.  .  .  . 

.  .      175 

'     60 

12 

Coupled  .... 

.  .      180 

60 

3 

Coupled.  .  .  . 

.  .     200 

60 

36 

Coupled.  .  .  . 

.  .     200 

60 

32 

Coupled.  .  .  . 

.  .     200 

25 

6 

Coupled.  .  .  . 

.  .     200 

50 

12 

Coupled  .... 

.  .     200 

60 

14 

Coupled.  .  .  . 

.  .     200 

60 

12 

Speed. 
300 
900 
257 
600 
900 
225 
277 
500 
750 
225 
227 
360 
514 
600 
900 
200 
600 
900 
200 
225 
500 
500 
514 
600 


Drive. 


K.W. 


Coupled 225 

Coupled 250 

Coupled 250 

Coupled 250 

Coupled 250 

Coupled 250 

Coupled 250 

Coupled 275 

Coupled 275 

Coupled 300 

Coupled 300 

Coupled 300 

Coupled 300 

Coupled 300 

Coupled 300 

Coupled 300 

Coupled 300 

Coupled 300 

Coupled 325 

Coupled 330 

Coupled 350 

Coupled 350 

Coupled 360 

Coupled 360 


Frequency. 

Poles. 

Speed. 

60 

12 

600 

60 

36 

200 

60 

32 

225 

60 

28 

257 

60 

24 

300 

60 

16 

450 

60 

12 

600 

60 

16 

450 

60 

12 

600 

60 

72 

100 

60 

48 

150 

60 

36 

200 

60 

32 

225 

60 

28 

257 

60 

24 

300 

60 

18 

400 

60 

16 

450 

60 

12 

600 

60 

36 

200 

50 

16 

375 

60 

16 

450 

60 

12 

600 

25 

8 

375 

25 

6 

500 

356 


HYDRO-ELECTRIC   PRACTICE 


TABLE   32.— STANDARD  GENERATORS,  ALTERNATORS,  2  AND  3  PHASE,  2300  VOLTS 

AND   UP. — Continued. 


Drive 

Coupled.  .  .  . 

K.W.   F 
.  .      360 

requency 
25 

.  Poles. 
4 

Speed. 

750 

Coupled.  .  .  . 

.  .     375 

60 

30 

240 

Coupled.  .  .  . 

.  .     380 

60 

16 

450 

Coupled.  .  .  . 

.  .     380' 

60 

12 

600 

Coupled  .  .  . 

.  .     400 

25 

20 

150 

Coupled.  .  .  . 

.  .     400 

60 

36 

200 

Coupled.  .  .  . 

.  .     400 

60 

28 

257 

Coupled.  .  .  . 

.  .     400 

60 

24 

300 

Coupled.  .  .  . 

.  .     400 

60 

16 

450 

Coupled.  .  .  . 

.  .     420 

60 

24 

300 

Coupled.  .  .  . 

.  .     420 

25 

18 

167 

Coupled.  .  .  . 

.  .     420 

25 

6 

500 

Coupled     .  . 

.  .     425 

60 

30 

240 

Coupled.  .  .  . 

.  .      425 

50 

16 

370 

Coupled.  .  .  . 

.  .      450 

60 

60 

120 

Coupled 

.  .     450 

60 

48 

150 

Coupled.  .  .  . 

.  .      450 

60 

40 

180 

Coupled.  .  .  . 

.  .      450 

60 

24 

300 

Coupled 

.      450 

60 

20 

360 

Coupled.  .  .  . 

.  .      450 

60 

36 

200 

Coupled.  .  .  . 

.  .      450 

60 

16 

450 

Coupled.  .  .  . 

.  .     450 

60 

12 

600 

Coupled  .... 

.  .     500 

25 

24 

125 

Coupled.  .  .  . 

.  .     500 

30 

20 

180 

Coupled.  .  .  . 

.  .     500 

60 

32 

225 

Coupled.  .  .  . 

.  .     500 

60 

26 

257 

Coupled.  .  .  . 

.  .     500 

60 

20 

360 

Couoled.  .  .  . 

.  .      500 

60 

16 

450 

Coupled.  .  .  . 

.  .      500 

60 

12 

600 

Coupled.  .  .  . 

.  .     500 

60 

6 

1200 

Coupled.  .  .  . 

.  .     540 

60 

36 

200 

Coupled.  .  .  . 

.  .     540 

25 

12 

250 

Coupled.  .  .  . 

.  .     540 

25 

10 

300 

Coupled.  .  .  . 

.  .     540 

60 

20 

360 

Coupled.  .  .  . 

.  .     540 

25 

8 

375 

Coupled.  .  .  . 

.  .     540 

25 

4 

750 

Coupled.  .  .  . 

.  .     550 

40 

10 

480 

Coupled.  .  .  . 

.  .     550 

60 

12 

600 

Coupled.  .  .  . 

.  .     600 

60 

36 

200 

Coupled.  .  .  . 

.  .     600 

60 

32 

225 

Coupled.  .  .  . 

.  .     600 

60 

20 

360 

Coupled.  .  .  . 

..     600 

25 

8 

375 

Coupled.  .  .  . 

..     600 

50 

16 

375 

Coupled  .  .  . 

..     600 

33 

10 

400 

Coupled.  .  .  . 

.  .     600 

60 

18 

400 

Coupled.  .  .  . 

.  .     600 

60 

16 

450 

Coupled     .  . 

..     600 

60 

12 

600 

Coupled.  .  .  . 

..     650 

60 

20 

360 

Couoled.  . 

700 

60 

20 

360 

Drive. 

K.W. 

Frequency. 

Poles. 

Speed. 

Coupled.  .  .  . 

..     700 

60 

18 

400 

Coupled.  .  .  . 

..     720 

25 

8 

375 

Coupled.  .  .  . 

..     750 

60 

60 

120 

Coupled.  .  .  . 

..     750 

60 

48 

150 

Coupled.  .  .  . 

..     750 

60 

40 

180 

Coupled  

..     750 

60 

36 

200 

Coupled.  .  .  . 

..     750 

60 

24 

300 

Coupled.  .  .  . 

..     750 

60 

20 

360 

Coupled.  .  .  . 

..     750 

60 

18 

400 

Coupled.  .  .  . 

..     800 

60 

36 

200 

Coupled.  .  .  . 

..     800 

60 

24 

300 

Coupled.  .  .  . 

..     900 

60 

56 

150 

Coupled  

..     900 

60 

48 

128 

Coupled.  .  .  . 

..     900 

60 

40 

180 

Coupled.  .  .  . 

..     900 

60 

20 

360 

Coupled.  .  .  . 

..     900 

60 

16 

450 

Coupled.  .  .  . 

..    1000 

60 

44 

163 

Coupled.  .  .  . 

..    1000 

60 

36 

200 

Coupled.  .  .  . 

..    1000 

60 

28 

257 

Coupled.  .  .  . 

..    1000 

60 

24 

300 

Coupled.  .  .  . 

..    1000 

60 

20 

360 

Coupled.  .  .  . 

..    1000 

60 

18 

400 

Coupled 

1000 

60 

16 

450 

Belted  

.  .  .      100 

60 

8 

900 

Belted  

.  ..     110 

30 

6 

600 

Belted  

.  .  .      125 

25 

6 

500 

Belted  

..  .      150 

60      . 

12 

600 

Belted  

.  ..     200 

25 

6 

500 

Belted  

...      150 

60 

12 

600 

Belted  

.  .  .     200 

25 

6 

500 

Belted  

.  .  .     200 

50 

12 

500 

Belted  

.  .  .     200 

60 

12 

600 

Belted  

.  .  .     250 

60 

20 

300 

Belted  

.  .  .     300 

60 

16 

450 

Belted  

.  .  .     300 

25 

6 

500 

Belted  

.  .  .     330 

50 

16 

375 

Belted  

.  .  .     425 

50 

16 

375 

Belted  

.  ..     450 

60 

20 

360 

Belted  

.  .  .     540 

25 

8 

375 

Belted  

.  .  .     540 

60 

20 

360 

Belted  

.  .  .     550 

40 

10 

480 

Belted  

.  .  .     600 

33 

10 

400 

Belted  

.  ..     600 

25 

8 

375 

Belted  

.  .  .     600 

50 

16 

375 

Belted  

.  ..     690 

60 

20 

375 

Belted  

.  .  .     650 

60 

20 

360 

Belted  

.  ..     750 

60 

24 

300 

1600 

1500 

1400 

1300 

1200 

1100 

1000 

900 

800 

700 

600 

500 

400 

300 

200 

100 


-»»B • 


M 


IT 


JJiagPHB 


«X 


16 
15 
14 
13 
12 

11 

10 


s> 


5 


T> 


Diagram    40 

Generators 
2300  Volt 
Dimensions 

for 
Preliminary  Use 


FT 


E7 


-Il^kvS. 


o 

10 


QO 


K.W. 


357 


358  HYDRO-ELECTRIC   PRACTICE 

ARTICLE  101. — The  transmission  plant  equipment  consists  of  trans- 
formers, the  line,  and  its  terminal,  the  substation. 

When  the  transmission  voltage  is  to  exceed  that  of  the  generator, 
which  is  generally  the  case  with  transmission  distances  exceeding  fifteen 
miles,  step-up  transformers  are  required  at  or  near  the  generating  plant, 
since  it  is  preferable  to  locate  them  in  a  separate  room  or  even  building 
from  that  where  the  generators  are  operating;  and  if  the  line  voltage 
exceeds  that  at  which  the  current  is  to  be  served,  which  will  almost 
always  by  the  case,  step-down  transformers  become  necessary  at  the 
terminal  of  the  line,  and  the  place  where  they  are  located  is  called  the 
substation.  It  may  be  noted  here  that  current  service  contracts  are 
frequently  made  for  the  delivery  of  the  current  at  line  voltage  to  the 
customer's  step-down  transformer;  this  is  especially  probable  when  such 
delivery  is  of  a  large  or  major  portion  of  all  of  the  transmitted  current, 
and  if  all  of  it  is  disposed  of  in  this  manner  there  is  no  need  of  a 
substation. 

It  is  understood  therefore  that  the  transformer  equipment  may 
consist  of  step-up  and  step-down  installations,  or  of  the  latter  only,  or 
that  none  may  be  required  as  a  part  of  the  power-plant  equipment. 

Transformers  are  of  the  same  design  and  construction  for  either 
service,  differing  only  as  to  the  winding  of  the  primaries  and  secondaries, 
as  has  been  explained  in  Article  97. 

The  line  consists  of  the  supports,  conductors,  and  fastenings. 

The  supports  may  be  timber,  concrete,  or  iron  poles  or  posts,  or 
steel-framed  towers,  their  choice  depending  upon  (a)  the  height  of  the 
conductors  above  the  surface,  (b)  the  length  of  the  spans  between  sup- 
ports, and  (c)  the  cost  of  available  material. 

The  line  conductor  may  be  of  copper  or  aluminum.  The  weight  of 
aluminum  wire  is  about  0.47  that  of  copper  wire  of  the  same  length  and 
resistance,  and  when  the  cost  of  aluminum  is  therefore  1  -r-  0.47  =  2.13 
that  of  copper  wire  or  less  the  aluminum  conductor  will  cost  no  more 
than  copper  conductor.  The  resistance  of  one  mil  foot  aluminum  wire 

is  17.0  ohms. 

Some  of  the  advantages  of  aluminum  wire  for  the  use  of  transmission 
line  conductors  are  that  sleet  will  not  readily  adhere  to  it,  on  account  of 
its  greasy  surface;  it  is  more  economically  transported  and  handled,  on 
account  of  its  lesser  unit  weight.  Some  of  the  disadvantages  are  that  it 
cannot  be  readily  soldered,  on  account  of  the  greasiness  of  the  surface, 


EQUIPMENT 


359 


and  therefore  joints  are  less  conveniently  made  than  with  copper  wire; 
also  its  surface  is  more  easily  injured  in  handling,  dragging  over  rough 
ground  or  stones,  because  of  its  greater  softness  than  that  of  hard  drawn 
copper  wire;  and,  as  the  melting  point  of  aluminum  is  much  lower  than 
that  of  copper,  there  is  more  danger  of  its  being  fused  by  arcing  across 
conductors. 

The  following  table  gives  some  of  the  characteristics  of  aluminum 
wire  which  are  to  be  considered  in  connection  with  its  use  for  electric 
transmission  line  conductors. 


TABLE  33.— ALUMINUM  WIRE. 

Elastic  limit  14,000  Ibs.  per  square  inch.       Ultimate  strength  26,000  Ibs.  per  square  inch.      Resistance 
quoted  is  at  75°  F.     Resistance  per  mil  foot  =  16.949  ohms. 

Area  in 
Size.  sq.  inch. 

500,000  cm 0.3930 

450,000  cm 0.3540 

400,000  cm 0.3141 

350,000  cm 0.2750 

300,000  cm 0.2360 

250,000  cm 0.1965 

0000  B.  &S 0.1661 

000  B.  &  S 0.1317 

00  B.  &S 0.1045 

0  B.  &  S 0.0829 

1  B.  &S 0.0657 

2  B.  &S 00521 

3  B.  &S 0.0413 

4  B.  &S 0.0327 

The  height  at  which  line  conductors  should  be  strung  will  principally 
be  determined  by  legal  requirements,  the  general  provisions  being  from 
30  to  35  feet  high  when  paralleling  highways  or  crossing  other  aerial 
wire  lines,  and  20  to  25  feet  when  strung  across  country.  It  is  therefore 
not  always  an  economical  programme  to  secure  transmission  line  loca- 
tions along  public  highways,  as  the  cost  of  the  higher  supports  may  be 
much  greater  than  the  cost  of  private  right  of  way  across  country,  the 
latter  affording  the  additional  important  advantage  of  guaranteeing  con- 
trol over  the  line  and  therefore  making  it  practicable  to  protect  it  against 
interference  from  the  public. 

The  length  of  the  span  is  determined  from  the  weight  of  the  conductor 
and  the  consequential  tension  which  is  developed  in  its  section,  and  the 
effects  due  to  the  temperature,  wind,  and  sleet.  Theoretically  the  sus- 


Lbs.  per 

Feet  per 

Ohms  per 

Ultimate  strength 

1000ft. 

pound. 

1000  feet. 

in  pounds. 

460 

2.041 

0.03082 

10,210 

414 

2.415 

0.03766 

9,190 

368 

2.718 

0.04237 

8,170 

322 

3.106 

0.04843 

7,150 

276 

3.623 

0.05652 

6,130 

230 

4.348 

0.06780 

5,110 

194.7 

5.733 

0.08010 

4,320 

154.4 

6.477 

0.10100 

3,430 

122.4 

8.165 

0.12740 

2,720 

97.1 

10.300 

0.16050 

2,150 

77.0 

12.990 

0.20250 

1,710 

61.0 

16.400 

0.25540 

1,355 

48.5 

20.620 

0.32200 

1,075 

38.5 

25.970 

0.40600 

852 

360  HYDRO-ELECTRIC   PRACTICE 

pended  wire  takes  the  form  of  a  catenary  between  supports,  but  it  is 
altogether  permissible  to  discuss  the  subject  by  considering  it  a  parabola, 
whereby  it  is  much  simplified  without  the  introduction  of  any  con- 
siderable error. 

If  L  is  the  length  of  the  span,  s  the  sag  of  the  wire,  its  deflection  from 
the  horizontal,  w  the  weight  of  the  wire  per  foot  length,  then  T  the  ten- 
sion =  L2Xw^-8sors  =  L2XwH-8T;  therefore  the  tension  of  a 
given  wire  varies  inversely  as  the  sag  for  the  fixed  span  length, 
and  for  given  tension  and  wire  the  sag  increases  as  the  square  of  the 
span  length. 

To  prevent  collision  of  the  wires  of  a  multiconductor  line  the  sag 
should  not  be  greater  than  twice  the  lateral  distance  between  conductors. 

The  tensile  strength  of  hard  drawn  copper  is  17  tons. 

The  tensile  strength  of  aluminum  is  16  tons. 

The  expansion  coefficient  for  copper  wire  is  0.0000096  per  degree  F. 

The  expansion  coefficient  for  aluminum  wire  is  0.0000128  per  degree  F. 

The  sag  of  the  span  may  be  found  from  these  values. 

Example. — 0000  copper  wire  is  to  be  strung  in  spans  of  120  feet 
length;  then  from  above  formula 

s  =  L2  X  w-=-8T,  where  L  =  120,  and  w  from  copper  wire  table  =  0.64  Ib. 
s  =  1202  X  0.64 -f-  (8  X  5460)  X  4;  this  latter  factor  represents  the  safety 

factor  for  normal  conditions. 
s=0.81  foot  or  9.75  inches. 

This  represents  the  minimum  admissible  sag  in  order  to  avoid  raising 
the  tensile  stress  above  the  basic  safety  factor  of  four,  and  from  this  the 
sag  which  is  necessary  to  compensate  for  contraction  due  to  low  tem- 
peratures must  be  found. 

If  this  line  is  to  be  constructed  in  the  Northern  latitudes,  in  Michigan, 
Wisconsin,  or  Canada,  a  low  temperature — minus  20°  F.  or  lower — must 
be  provided  for,  and  for  this  condition  the  proper  sag  is  to  be  found  from 
the  actual  length  of  the  conductor  in  the  span  which  is  based  upon  the 
minimum  sag  as  shown  above.  Thus, 

Lw  (the  length  of  the  conductor  in  the  span)  =  L  +  8sJ  -f-  3L, 
or  Lw  for  above  example  =  120  +  8(0.8P)  -=-  360 

=  120.0146  feet, 


EQUIPMENT  361 

If  we  assume  the  normal  summer  temperature  at  65°  F.,  then  the 
difference  in  temperature  to  be  compensated  for  by  increased  sag  will 
be  85°,  and  the  contraction  of  the  copper  wire  will  be 

=  85  X  0.0000096  X  120.0146  =  0.098  foot,  which  must  be  added  to 
the  length  Lw  =  120.0146  +  0.098  =  120.1026  feet. 


The  sag  will  be,  from  Lw  =  Lx8s2-r-3Lors=  ^'3L  (Lw  -  L)  -s-  8, 
for  this  case  s    =  ^360  (120.1026  --  120)  •*•  8  =  30  inches. 

The  safety  factor  in  transmission  line  wire  calculations  should  be 
adjusted  to  the  climatic  condition  of  the  locality;  if  the  prevalent  wind 
movements  are  ordinary  and  no  sleet  storms  to  be  expected,  the  factor 
of  four  above  used  is  sufficient  for  practical  purposes;  where  high  winds 
prevail,  such  as  should  be  credited  with  pressures  of  40  and  50  Ibs.  per 
square  foot,  or  if  sleet  storms  are  of  yearly  occurrence,  the  factor  must 
be  raised  to  six,  and,  in  specially  exposed  locations,  as  for  instance  along 
the  shores  of  the  ocean  or  the  Great  Lakes,  the  factor  should  be  taken 
at  eight. 

For  aluminum  wire  the  same  method  of  calculating  the  span  length 
and  the  sag  applies,  provided  the  proper  values  of  weight,  tensile  strength, 
and  expansion  coefficient  are  substituted. 

The  ordinary  practice  is  to  make  spans  of  a  timber-pole  line  from  90 
to  150  feet  long;  106  feet  is  taken  very  commonly,  requiring  fifty  poles 
to  the  mile. 

Steel-framed  towers  are  chiefly  used  when  the  transmission  line  is 
of  double  conductor  circuits,  which  is  always  recommendable  with  high 
line  voltage  and  large  output  plants ;  such  towers  are  fifty  feet  and  higher 
and  the  spans  correspondingly  longer. 

Watercourses  or  wide  swamps  may  have  to  be  crossed  on  trestles. 
Submarine  cables  are  rarely  applicable  in  high- voltage  transmission; 
they  require  an  extra  set  of  step-up  and  step-down  transformers,  as  they 
are  not  reliable  for  any  higher  pressure  than  about  3000  volts. 

Supports  for  a  height  of  line  conductors  up  to  35  feet  may  be  of 
timber  poles;  they  should  be  set  one-seventh  of  their  length  into  the 
ground,  the  buried  portion  and  one  foot  above  the  surface  being  well 
tarred,  and  the  top  wedge  shaped  and  painted.  Concrete  poles  are  now 
being  constructed  economically  and  make  excellent  line  supports. 


362  HYDRO-ELECTRIC   PRACTICE 

Steel-framed  towers  may  be  of  various  designs;  some  are  shown  on 
Fig.  134. 

Conductor  fastenings  consist  of  cross-arms,  insulator  pins,  and 
insulators. 

Cross-arms  (Fig.  134)  are  rectangular  pieces  of  timber  3|  X  4|  X 
4  to  5  feet  long,  or  3f  X  4f  X  6  to  8  feet  long.  They  are  preferably  of 
yellow  pine  which  is  kiln  dried  and  well  boiled  in  linseed  oil,  and  they 
are  slightly  rounded  on  top  the  better  to  shed  the  rain.  Cross-arms  are 
secured  to  the  poles  by  being  gained  1^  inches  and  fastened  with  a  }- 
inch  round  wrought-iron  screw  bolt  passing  through  the  cross-arm  and 
the  pole.  The  longer  cross-arms  should  be  further  secured  to  the  pole 
by  two  diagonal  braces,  which,  for  high  voltage  lines,  should  be  of 
hard  wood  instead  of  iron  straps.  The  upper  cross-arm  is  placed 
about  two  feet  below  the  pole  top,  and  the  others  are  spaced  in 
accordance  with  the  distance  required  between  conductors,  being  from 
two  to  three  feet. 

Insulator  pins  (Fig.  135)  form  a  very  important  part  of  the  line. 
They  carry  the  insulators,  to  which  the  conductors  are  secured,  and 
are  fastened  to  the  cross-arms;  they  have  to  take  up  and  resist  all  the 
lateral  strain  to  which  the  conductors  are  exposed,  and  they  also  form  the 
only  available  path  for  current  leakage.  Therefore  they  must  be  of 
suitable  material,  sufficient  section,  securely  connected  to  their  sup- 
ports, the  cross-arms,  and  should  be  well  insulated.  Insulator  pins  are 
preferably  of  oak  or  locust;  they  should  not  be  of  iron  where  high  volt- 
ages are  to  be  transmitted.  Small  section  pins  are  to  be  avoided;  they 
should  be  not  less  than  2J  inches  in  diameter  and  10  inches  long,  and  as 
much  heavier  in  section  and  longer  as  the  weight  of  the  conductor,  which 
is  to  be  secured  to  the  pin,  requires.  Insulator  pins  must  be  thoroughly 
dried  and  well  boiled  in  linseed  oil.  Pins  are  set  into  holes  bored  in  the 
top  faces  of  cross-arms  and  secured  by  a  treenail  driven  through  the 
shank  of  the  pin  and  the  cross-arm;  spikes  should  not  be  used  for  this 
purpose.  The  top  end  of  the  insulator  pin  is  threaded  for  about  three 
inches  to  receive  the  insulator. 

Insulators  (Fig.  135)  carry  the  conductor.  They  are  made  of  glass, 
porcelain,  or  earthen-ware,  consisting  of  one  or  more  superposed  bells 
(petticoats  so  called) ,  their  purpose  being  to  shed  the  rain  away  from  the 
insulator  pin.  Insulators  should  be  tested  for  the  voltage  to  be  trans- 
mitted and  for  their  breaking  strength.  The  conductor  passes  over  the 


Transmission  line 
Towers  &  Poles 


Reinforced 

Concrete 

tower 


;  \\^\\v<%V^%=\\\^\\\^W^\\Ng 

T^^*flw» 


Structural    steel 
tower 


363 


364  HYDRO-ELECTRIC   PRACTICE 

top  of  the  insulator,  lying  in  a  groove,  and  is  secured  to  the  insulator  by 
a  wire  binding. 

The  substation  is  a  suitable  structure  where  the  line  terminates,  and 
contains  the  required  switchboard,  the  reorganizing  and  transforming 
equipment. 

The  entry  of  the  line  conductors  into  the  substation  must  be  carefully 
planned.  It  is  generally  effected  by  passing  the  conductors  through 
insulator  disks  set  into  circular  openings,  of  12  inches  or  larger  diameter, 
in  the  wall  of  the  substation  building,  with  some  shelter  over  the  point 
of  entry  to  protect  the  conductors  at  the  entry  from  rain  and  snow. 

This  closes  the  treatment  of  the  electrical  equipment  of  a  hydro- 
electric plant,  which  has  been  necessarily  very  brief,  as  its  detail  dis- 
cussion would  assume  the  proportions  of  a  separate  volume. 

Figs.  136  to  140  give  some  general  views  of  the  partial  installation 
of  electrical  equipment  of  the  hydro-electric  plant  at  Sault  Ste.  Marie, 
Mich.;  the  output  capacity  is  about  32,000  kilowatts  in  80  units  of 
400  kilowatts.  Both  continuous  and  alternating  currents  are  being 
generated;  the  speed  of  all  direct-connected  generators  is  180  revolutions 
per  minute.  This  plant  was  designed  by  the  author  and  constructed 
under  his  charge  as  chief  engineer. 

Fig.  136  shows  the  sectional  armature  of  a  400-kilowatt  3-phase 
30-cycle  alternator,  and  Fig.  137  the  revolving  field  of  the  same  machine. 

Fig.  138  presents  a  fine  modern  specimen  of  a  continuous-current 
400-kilowatt  dynamo  coupled  to  the  turbine  shaft,  and  Figs.  139  and 
140  give  a  general  view  of  the  partial  generator  installation.  In  Fig. 
139  the  first  three  machines  are  D.  C.  dynamos,  the  others  are  alter- 
nators; the  switchboard  panels  are  on  the  left,  which  was  a  temporary 
arrangement,  as  they  were  finally  placed  along  the  wall  on  the  right 
upon  elevated  platforms;  in  the  foreground  of  Fig.  140  stands  a  rotary 
converter. 

ARTICLE  102.  Auxiliary  Power  Plant. — A  very  good  and  learned 
friend  of  the  author  remarked  once  that  he  could  always  find  a  hydro- 
electric plant  by  looking  for  a  smoke-stack  near  a  river,  and  this  is  as 
it  generally  should  be  if  the  development  is  a  complete  utilization  of 
the  opportunity.  It  is  only  exceptionally  that  the  net  earning  capacity 
of  a  hydro-electric  plant  cannot  be  materially  enhanced  by  the  addition 
of  a  supplementary  plant;  this  indeed  is  only  the  case  when  nature  has 
provided  a  well-balanced  ratio  of  power  functions  by  furnishing  a  con- 


Fig.,    135 


High  Tension 


Low  Tension 


Insulators  &  Pins 


Section  c-  d 


b    d 


H.E.P. 
H.  v.  S. 


213 


365 


366  HYDRO-ELECTRIC   PRACTICE 

stant  volume  of  flow  and  non-fluctuating  head,  or  by  supplying  the 
means  to  maintain  such  an  equilibrium  in  the  shape  of  sufficient  reservoir 
capacity.  It  is  precisely  the  degree  of  deficiency  of  the  natural  supply, 
or  of  facilities  to  accomplish  this,  which  represents  the  utility  of  the 
auxiliary  plant,  provided  always  that  a  demand  for  the  current  exists. 

It  is  not  the  intention  to  go  into  any  of  the  details  of  this  topic 
here,  as  to  the  character  and  the  make-up  of  the  auxiliary  power  plant, 
whether  it  should  be  a  plant  of  steam  boilers  and  engine  or  steam  tur- 
bine, or  whether  oil  or  gas  engine,  this  forming  a  topic  of  operation  rather 
than  equipment.  Here  it  must  suffice  to  remind  the  investigator  that 
the  design  and  estimate  of  a  hydro-electric  plant  is  generally  incomplete 
without  taking  into  consideration  this  feature  of  an  auxiliary  power 
plant.  Therefore  the  power  station  should  be  located  and  designed  with 
this  probable  future  requirement  in  view.  The  capacity  of  the  auxiliary 
should  be  prima  facie  of  at  least  one  generator  unit,  and  in  this  respect 
may  influence  the  determination  of  the  unit  question.  The  auxiliary 
plant  will  be  rarely  called  for  until  the  hydro-electric  plant  has  been  in 
operation  some  years,  but  in  estimating  upon  the  whole  project  and 
deducing  the  net  earning  capacity  of  the  proposed  enterprise  this  factor 
must  be  included  as  an  item  of  investment,  of  maintenance  and  depre- 
ciation charge,  and  of  operating  cost. 

The  storage  battery  or  accumulator  should  also  be  considered  as  an 
auxiliary  power  plant  factor.  It  consists  of  two  inert  metal  plates,  or 
of  metallic  oxides,  which  are  placed  in  glass,  earthen-ware,  or  wooden 
receptacles  holding  an  electrolyte,  which  is  a  compound  liquid  separable 
into  its  constituent  ions  by  the  passage  of  electric  currents  through  it. 
A  storage  battery  is  a  collection  of  such  elements  chargeable  by  contin- 
uous current,  which  produces  decomposition  of  the  inert  electrolyte 
between  plates,  whereby  cathions,  electro-positive  radicals,  are  deposited 
on  the  plate  which  is  connected  with  the  negative  pole  of  the  charging 
generator,  and  anions,  the  electro-negative  radicals,  on  the  plate  which 
is  connected  to  the  positive  pole  of  the  charging  source.  When  the  ter- 
minals of  such  a  storage  battery  which  is  charged  are  connected  outside 
of  the  electrolyte,  an  electric  current  is  set  up,  flowing  from  the  plate  on 
which  the  positive  radicals  are  deposited  to  that  of  the  negative  radicals, 
which  is  in  direction  opposite  to  that  of  the  charging  current.  It  may 
be  noted  here  that  it  is  erroneous  to  speak  of  the  storing  of  the  electric 
current,  since  the  charging  current  is  simply  the  means  of  and  initiates 


^ 

-     ! HE   "      \ 
iSiTY  ) 


H.  v.  S. 


EQUIPMENT  367 

the  setting  up  of  the  battery  current  caused  by  the  decomposition  of  the 
electrolyte,  as  above  briefly  outlined.  Storage  battery  elements  ordinarily 
represent  electro-motive  force  of  from  2^  volts  up,  but  their  range  is 
very  limited.  They  may  be  charged  by  the  surplus  output  of  the  hydro- 
electric plant  and  discharged  to  add  to  the  generating  plant  output  in 
supplying  additional  current  to  carry  the  maximum,  the  peak,  loads,  and 
in  small  installations,  when  night  water  storage  is  necessary  during  low- 
flow  seasons  to  accumulate  the  necessary  day-load  water  supply,  accumu- 
lators of  this  type  can  frequently  be  utilized  to  take  care  of  the  part  night 
current  loads  made  up  of  lighting  business.  Storage  plants  are  also 
used  for  regulation  purposes,  and  may  then  be  located  at  the  generating 
plant  or  along  the  transmission  line;  when  they  are  to  carry  part  loads 
they  are  preferably  placed  at  the  substation. 


CHAPTER    X 

CONSTRUCTING   THE    PLANT 

THE  burden  of  all  that  has  gone  before  is  encompassed  in  the  topic 
of  this  chapter,  the  realization  of  the  development,  and  it  does  not  seem 
essential  to  the  treatment  of  the  subject  of  hydro-electric  practice  to  go 
very  far  either  into  the  generalities  or  the  details  of  this  topic,  which  for 
hydro-electric  plants  does  not  necessarily  present  features  which  may 
not  be  found  in  the  construction  of  other  works.  However,  something, 
the  author  feels,  should  be  said  of  the  preparations  for  this  final  step,  the 
construction,  and  of  some  features  which  are  perhaps  peculiar  to  this 
particular  class  of  structures. 

ARTICLE  103.  Plans. — The  proper  plans  for  a  hydro-electric  plant 
are  perhaps  much  more  complex  than  those  of  any  other  single  engineer- 
ing undertaking,  as  they  cover  the  wide  range  represented  by  hydraulics, 
hydrostatics,  structures  of  timber,  earth,  rock,  masonry,  concrete,  rein- 
forced concrete,  steel,  hydrodynamics,  mechanics,  and  electrical  theories 
and  practice;  and  they  must  necessarily  be  elaborate  in  details  based 
upon  calculations  of  functions,  factors,  dimensions,  sections,  etc.,  per- 
taining to  all  these  various  branches.  Every  pertinent  detail  should 
be  designed  to  a  sufficiently  large  scale  readily  to  detect  errors  and, 
wherever  practicable,  algebraic  calculations  should  be  checked  diagram- 
matically. 

All  calculations  should  be  made  in  a  computation  book  devoted  to 
that  particular  project,  and  in  a  clear  and  precise  manner,  preferably  in 
ink,  each  separate  calculation  of  importance  should  be  given  a  separate 
page,  and  when  this  book  is  completed  with  a  comprehensive  index  it 
will  prove  a  great  labor  and  trouble  saver  in  the  future  checking  and 
even  during  the  construction  progress.  All  sheets  containing  plans  should 
be  of  uniform  size;  dimensions  should  be  given  in  figures  and  identified 
by  dimension  lines;  the  lettering  should  be  plain;  the  author  uses  stamp- 
ing machines  for  this  purpose  wherever  practicable.  Every  structural 
feature  should  be  shown  in  location,  plan,  longitudinal  and  transverse 
sections,  followed  by  each  important  detail,  and  these  latter  should  be 
numbered  consecutively  throughout  the  entire  set  of  plans. 

368 


CONSTRUCTING  THE  PLANT  369 

Originals  should  be  inked  before  any  of  them  are  traced,  which  will 
obviate  errors  caused  by  the  misinterpretation  of  pencil  designs  on  the 
part  of  the  tracer. 

ARTICLE  104. — Estimates  should  never  be  made  until  the  designs  are 
completed  and  checked,  and  their  original  form  should  take  the  shape  of 
a  comprehensive  detail  tabulation,  giving  title  of  structure,  number  of 
detail  and  sheet,  dimensions,  quantities,  and  unit  price  of  cost  of  material 
and  of  operation.  The  delivery  cost  of  the  material  must  be  fully  covered, 
as  well  as  the  insurance  of  construction  plant,  material,  and  of  the  per- 
sonnel employed.  A  net  profit  of  at  least  15  per  cent,  should  be  added, 
and  finally  ten  per  cent,  must  be  allowed  for  engineering  and  control. 

Estimates  should  be  analytical,  as,  for  instance, 

Concrete  of  1  :  2  :  4  mixture: 

1J  bbl.  Portland  cement,  deld.,  @  2.25  per  bbl $3.38 

\  cub.  yd.  sand,  deld.,  @  1.00  per  cub.  yd 0.50 

1  cub.  yd.  broken  stone,  deld.,  @  0.75 0.75 

Mixing  by  machine 0.30 

Conveying  to  site  by  barrows 

Placing  concrete,  monolithic,  or 

Placing  concrete  in  forms,  at  respective  price 

Timber  forms,  used  three  times,  cost  of  lumber  deld.,  $30.00  per  1000  ft.  b.  m.  per 

cub.  yd. 

Removing  forms  per  cub.  yd.,  according  to  dimensions  of  structure 
Finishing,  if  outside  wall  floor  or  facing. 

Every  item  should  be  treated  this  way  in  estimating  its  cost.  And 
finally  the  estimate  should  be  concluded  by  a  summing  up  of  all  the 
different  material  required  and  grouped  in  accordance  with  proper 
classifications  as  to  its  character  and  cost. 

ARTICLE  105.  Specifications. — The  practice  in  this  respect  is  so  cha- 
otically diversified  that  it  may  almost  be  called  an  individual  business. 
The  author  believes  this  subject  should  be  approached  as  far  as  practicable 
from  the  view-point  of  the  constructor,  with  a  full  realization  of  his  posi- 
tion, if  he  is  seriously  inclined  to  make  a  proper  tender.  The  principal 
purpose,  it  seems,  therefore,  is  to  convey  clearly  the  ideas  and  intentions 
of  the  designer  of  the  plant.  The  structures  of  a  hydro-electric  plant  dif- 
fer considerably  from  those  of  like  general  character  for  other  purposes. 
For  instance,  a  diversion  canal  appears  to  many  constructors  not  at  all 
different  from  any  other  kind  of  water  way,  merely  to  pass  the  water, 
while  it  is,  or  should  be,  designed  in  accordance  with  definite  scientific 
principles,  and  must  be  constructed  in  strict  conformity  to  these  in  order 

24 


370  HYDRO-ELECTRIC   PRACTICE 

that  the  desired  results  be  fully  realized.  So  it  is  with  the  power  station, 
which  appears  to  be  simply  an  ordinary  kind  of  building,  while  in  fact 
it  is  one  of  very  peculiar  and  important  details  not  met  with  in  other 
building  structures  of  even  much  heavier  masonry  sections.  Earth 
embankments  seem  so  much  like  those  so  common  in  railroad  construc- 
tion that  it  is  an  exceedingly  difficult  task  to  create  the  proper  impression 
of  their  absolute  specific  purpose  and  therefore  their  entirely  different 
construction.  And  so  on  along  the  line  from  the  first  to  the  last,  and 
for  these  reasons  the  specifications  for  a  hydro-electric  plant  cannot  be 
too  specific  in  clearly  conveying  their  purpose,  followed  by  the  explicitly 
definite  detailing  of  the  structural  methods  by  which  these  results  are 
to  be  secured. 

It  is  also  well  to  bear  in  mind,  when  one  prepares  specifications, 
that  the  main  purpose  is  to  get  this  plant  constructed,  and  to  have  this 
done  as  expeditiously  and  economically  as  can  be,  and  have  it  done  well, 
and  that  such  results  can  only  be  hoped  to  be  secured  by  a  complete 
co-operation  between  the  constructor  and  the  engineer  looking  after  the 
interests  of  the  owners.  It  is  absolutely  useless  in  this  respect,  in  the 
author's  judgment,  to  burden  the  specifications  with  restrictions  of  the 
constructor's  freest  latitude  of  utilizing  his  own  experience  and  ingenuity 
for  the  purpose  of  securing  the  best,  speediest,  and  most  economical 
realization  wherever  practicable.  Methods  so  specified,  but  made  appli- 
cable or  not  solely  upon  the  dictum  of  the  engineer,  or  elastic  conditions 
depending  upon  the  future  interpretation  or  decision  of  the  engineer, 
are  calculated  only  to  inject  costly  uncertainties  into  the  undertaking,— 
that  is,  costly  to  the  owners  of  the  plant,  not  to  the  contractor,  who  is 
forced  by  all  considerations  of  self-protection  to  discount  them  heavily, 
as  it  is  not  his  province  to  take  chances. 

Quantities  should  always  be  quoted  in  positive  figures;  if  they 
are  uncertain  the  specifications  should  so  state,  and  the  probable 
fluctuations  should  be  provided  for  upon  a  fixed  and  equitable  basis 
of  values. 

The  majority  of  specifications  contain  severe  penalties  for  default 
in  completing  the  works  within  a  specified  or  agreed-upon  time  limit; 
few,  however,  provide  any  reward  for  anticipation  of  such  a  limit.  Again, 
it  is  not  to  be  expected  that  the  enterprise  is  to  be  financed  by  the  con- 
tractor, who  should  receive  such  a  percentage  of  his  earnings  that  they 
vail  meet  his  actual  outlay. 


CONSTRUCTING  THE  PLANT  371 

These  are  generalities,  nor  can  the  subject  be  treated  in  any  other 
manner, — that  is,  no  hard-and-fast  form  can  be  defined  as  adapted  to 
any  certain  range  of  conditions. 

As  to  details,  the  author's  meaning  is  best  illustrated  by  an  example. 

Specifications  of  the  Anchoring  of  a  Spillway  in  Rock  Location. 

1.  The  site  of  the  spillway  is  shown  on  Plan  3  and  the  dimensions  are  as  thereon 

given. 

2.  All  elevations  are  referred  to  Bench  mark  "  D,"  being  the  top  of  an  iron  bolt 

2  inches  in  diameter,  which  is  set  and  leaded  in  the  top  of  a  granite  boulder 
on  the  west  side  of  the  river  on  the  north  line  of  the  spillway  location, 
as  shown  on  Plan  3,  and  about  15  feet  from  the  crest  of  the  natural 
bank;  the  elevation  of  this  bench  is  654.76  ft.  above  mean  tide,  New 
York. 

3.  So  much  of  this  area  as  can  be  conveniently  coffered  against  the  water  at 

one  time  is  to  be  entirely  freed  from  all  water,  and  is  to  be  maintained  in 
this  condition  at  all  times  until  the  constructions  described  in  this  article, 
"Anchoring  the  Spillway,"  are  fully  completed,  inspected,  and  accepted 
by  the  engineer. 

4.  The  methods  of  coffering  and  of  maintaining  the  dry  condition  may  be  as 

elected  by  the  contractor. 

5.  The  area  is  to  be  cleaned  of  all  vegetable  and  earthy  substances,  and  all 

loose  rock  or  such  as  can  be  dislodged  from  the  ledge  by  the  ordinary 
use  of  a  12-lb.  miner's  pick,  which  is  to  be  removed,  and  the  material  thus 
taken  up  may  be  disposed  of  as  the  contractor  elects. 

6.  Anchor  holes  of  the  size  and  to  the  depth  shown  in  Detail  22  on  Sheet  11  are 

to  be  drilled  into  the  rock  bed  and  freed  from  all  loose  stone:  they  are 
to  be  spaced  as  shown  in  location  Plan  3. 

7.  Anchor  bolts  of  3-inch  round  wrought  iron  4  feet  long  are  to  be  set  in  the 

anchor  holes,  the  bottom  six  inches  of  the  bolts  being  split  open  by  one 
cut  and  spread  to  a  diameter  of  3£  inches.  Grouting,  consisting  of  one 
part  Portland  cement,  two  parts  of  sand,  and  three  parts  of  fine  gravel, 
is  to  be  poured  into  the  hole  while  the  anchor  bolt  is  being  held  at  the 
bottom  and  in  the  centre  of  it. 

8.  The  anchor  bolts,  cement,  sand,  and  gravel,  and  the  mixing  of  the  grouting 

are  to  conform  to  the  specified  material  and  method  as  given  in  the  second 
article  of  these  specifications. 

In  other  words,  there  is  no  operation  so  unimportant  but  that  it 
deserves  to  be  clearly  analyzed  and  so  described  in  the  specifications. 

ARTICLE  106. — Engineering  control  of  the  construction  of  this  kind 
of  a  plant  cannot  be  any  too  thorough;  short-sighted  economy  in  this 
respect  may  be  exceedingly  expensive  in  the  end. 


372  HYDRO-ELECTRIC   PRACTICE 

All  material  should  be  inspected  and  tested;  each  operation  should 
be  carefully  overseen;  and,  no  matter  how  small  the  plant,  the  author 
has  always  found  it  justifiable  to  keep  a  daily  progress  record  of  each 
separate  construction  feature  on  specially  prepared  forms,  of  the  time 
performance  and  therefore  the  cost;  such  a  record  is  as  valuable  to  the 
contractor  as  it  is  to  the  owner  and  certainly  to  the  engineer.  Nor 
should  the  camera  be  omitted  in  chronicling  progress  stages.  Such  a 
plant  well  constructed  is  a  monument  to  all  the  parties  concerned,  and 
to  the  engineer  who  conceives  and  brings  it  into  activity  it  should  be  a 
source  of  pride  and  satisfaction. 

If  the  man  who  makes  two  blades  of  grass  grow  where  formerly 
was  only  one  is  entitled  to  the  plaudits  of  mankind,  how  much  more  is 
he  who  harnesses  the  now  wasting  energy  of  falling  water! 


GENERAL  INDEX 


PAGE 

Abutment,  quantities    for,    Diagram    12 ...      66 

Abutment,  spillway,  described 209 

Accumulator    (see  Storage  battery) 

Air  vents  in  spillways 235 

Alluvials,  characteristics    of 132 

Alternate  current,  definition 333 

Aluminum  wire 346-358 

Aluminum  wire,  characteristics,  Table  33..    359 

Ammeters   349 

Amp&re,  definition    of 331 

Ampdre  turns,  definition  of 333-338 

Analysis  of   current   market 4 

Analysis  of  hydro-electric  project 1 

Apron  of  solid  spillway,  form  of 186 

Arc  lights,  service 1 

Armature,  dynamo,  description 340-342 

Armature  winding,  description 340-342 

Auxiliary  power,  definition 42 

Auxiliary  power  plant 364 

Auxiliary  power,  value  of 44 

Backswell  above  dam,  analyzed 149 

Backswell  above  dam,  definition  of 149 

Backswell  slope,  Diagrams  20-25 152-156 

Backswell  slope,  formula  for 149 

Base  benches  (survey) ,  Fig.  1 92 

Bearing  piles,  capacity 138 

Bearing  piles,  description  of 138 

Bear-traps,  described 198 

Benches,  base,  for  survey,  Fig.  1 92 

Block  concrete,  definition  of 140 

Boom,   floating 230 

Booster,   definition 350 

Borings,  Figs.  7  and  8 99-100 

Brackets,  supporting,  for  survey,  Fig.  1 ....  92 

Breakwater,  description  of 142 

Bulkheads,  concrete  steel 226 

Bulkheads,  reservoir,  quantities,  Diagram  15  72 
B.  &  S.    (Brown  &  Sharpe)   gauge  of  wire, 

Table  31 340 

Canal,  designs  of  bed  and  sides 244 

Canal  headgates 246 


PAGE 

Canal   intake 246 

Capacity,  current,  definition 336-347 

Case  of  reaction  turbine 292 

Cement,  Portland,  specifications  of 139 

Central  discharge  reaction  turbine,  descrip- 
tion of 294 

Central    discharge   reaction   turbine,   design 

of,  Fig.   113 295 

Channels,  curved,  slope  in 242 

Channels,  open,  flow  in,  theory  of 236 

Channels,  open,  slope  in,  Tables  16-19.  .   238-239 
Channels,  open,  velocity  in,  Tables  20-24 .  . 

240-241 
Charges,    fixed,    for   plants   500-1000    H.  P., 

Diagram  5 57 

Charges,  fixed,  for  plants   1000-5000  H.  P., 

Diagram  6 58 

Charges,  fixed,  for  plants  5000-10,000  H.  P., 

Diagram  7 59 

Choking  coil,  definition 350 

Circular    mil     measurement     of    aluminum 

wire;  Table  33 359 

Circular   mil   measurement   of  copper  wire, 

Table  31 340 

Classification  of  turbines 285 

Clay,  characteristics  of 133 

Clay  for  earth  dam 226 

Coefficient  of  perimeter  roughness 103-237 

Coffering,    definition    of 135- 

Coffering,  description  of 143: 

Coffer  structures,  quantities  for,  Table  8.  .  .    144 
Collector    (see  Commutator) 

Commutator,  description  of 336-341 

Compound  winding  of  field  magnets 338; 

Concrete,  block,  definition  of 140) 

Concrete,  characteristics  of,  Table  4 140) 

Concrete,  cost  of,  Diagram  11 65 

Concrete,  cyclopean,  definition  of 140 

Concrete,  monolithic,  definition  of 140 

Concrete,  reinforced,  definition  of 140 

Concrete-steel  beams,  constants  of,  Table  6.    141 

Concrete-steel  beams,  designs,  Table  7 141 

Concrete-steel  bulkhead 226 

373      . 


374 


GENERAL   INDEX 


PAGE 

Concrete-steel  dam,  quantities  for,  Diagram 

10 64 

Concrete-steel,     definition     and     description 

of 139,  140 

Concrete-steel  piles,  description  of 138 

Concrete-steel  pipe,  cost  of 67 

Concrete-steel  retaining  walls,  described.  .•.  .  214 

Congressional  act  for  power  project 47 

Constants  for  concrete-steel  beams,  Table  6.  141 
Constants    of    flow    over    flat-crested    weirs, 

Diagram  2 39 

Constants  of  flow  in  open  channels,  Tables 

16,  24 238,  241 

Constants  of  flow  through  overflow  sluices.  .  195 
Constants  of  flow  in  pipes,  Tables  27-29.250,251 

Constants  of  flow  through  underflow  sluices .  195 
Constants    for    gravity    spillway    sections, 

Tables   10-14 191-194 

Constants    of    impulse    wheel    output,    Dia- 
gram  39 323 

Constants  of  reaction  turbine  output,  Dia- 
gram  38 319 

Constants  for  normal  solid  spillway  sections, 

Table  10 185 

Constructing  the  plant 90 

Constructing  the  plant,  engineering  control.  371 

Constructing  the  plant,  estimates 369 

Constructing  the  plant,  plans 368 

Constructing  the  plant,  specifications 369 

Continuous   current,   definition 336 

Continuous  current  dynamos 337 

Continuous  current  transmission 346 

Control  of  Government  over  rivers 47 

Control  of  rivers  by  War  Dept.,  Table  3.  .  .  50 

Control  of  rivers  by  States 53 

Copper  wire,  characteristics  of,  Table  31.  ..  340 

Copper  wire,  resistance  of,  Table  31 340 

Copper  wire,  weight  of,  Table  31 340 

Core  wall,  description  of 139 

Correctors   (see  Lightning  arresters) 

Cost,   comparative,   of   timber  and   concrete 

spillways,  Diagram  30 211 

Cost  of  concrete,  Diagram  11 65 

Cost  of  dam 61 

Cost  of  development 61 

Cost  of  diversion  works 67 

Cost  of  pipe,  concrete  steel 67 

Cost  of  pipe,  steel  plate 67 

Cost  of  pipe,  wood  stave 67 

Cost  of  power  equipment 70 

Cost  of  substation 70 

Cost  of  transformers .  .  70 


PAGE 

Cost  of  transmission  line 70 

Cribs,  log,  description  of 136 

Cribs,  timber,  description  of 137 

Cross-arms,  transmission  line 361 

Crushing  of  spillway,  theory  of 170 

Current,    alternate 333 

Current  alternations,  definition  of 333 

Current    capacity 336-347 

Current,  continuous 336 

Current  frequencies,  definition  of 335 

Current  to  be  generated,  determined 350 

Current  impedance 336 

Current   inductance 335 

Current  market,  analysis  of 4 

Current  market,  canvass  for 5 

Current,  monophase 331 

Current  phase 335 

Current,  polyphase 335 

Current  rates,  H.  P.  and  K.  W.,  Diagram  8.  60 

Current    reactance 336 

Current  reaction 335 

Current  regulation 348 

Current  reorganization 342 

Current,  self-induction  of 335 

Current  service,  industrial 2 

Current  service,  lighting 1 

Current  service,  special 2 

Current  service,  traction 4 

Current,  single-phase 335 

Current  transformation 343 

Current  transmission 345 

Current,  three-phase 335 

Current,   two-phase 335 

Current,  wattless 336 

Curtain,  steel,  description  of 139-146 

Curtain,  timber,  description  of 139-146 

Curved  channels,  slope  in 242 

Cut-off  wall,  description  of 139 

Cut-off  wall,  quantities  for,  Table  9 147 

Cyclopean  concrete,  definition  of 140 

Cylinder  gate  of  turbine 289 

Dam,  concrete-steel 64 

Dam,  cost 61 

Dam,  description,  general 131 

Dam,  earth  and  rockfill 222 

Dam,  foundation,  detail  description. .  . .    144-147 

Dam  foundation,  functions  of 131 

Dam,  height  of,  analyzed 149 

Dam,   hydraulic-fill 226 

Dam,  length  analyzed 149 

Dam,  masonry,  dimensions,  Diagram  9 63 


GENERAL   INDEX 


375 


PACK 

Dam,  masonry,  quantities,  Diagram  9 63 

Dam,  reservoir,  described 221 

Dam  and  spillway  appurtenances 227 

Dam,  superstructure  of 148 

Design  of  canal  bed  and  sides 244 

Design  of  central  discharge  turbine,  Fig.  113  295 

Design  for  foundation,  Fig.  18 145 

Design  for  foundations 144 

Design  of  gravity  spillway,  Tables  11-14  191-194 
Design  of  gravity  spillway,  characteristics, 

Table  14 194 

Design  of  horizontal  turbines,  four,  paired 

and  drowned,  Fig.  119 312 

Design   of   horizontal   turbines,   paired   and 

cased,  Figs.   120,   121 313,  315 

Design   of   horizontal    turbines,   paired   and 

drowned,   Fig.   117 306 

Design  of  horizontal  turbines,  three  paired 

and  drowned,  Fig.  118 309 

Design  of  impulse  wheel,  Fig.  114 297 

Design  of  power  house  for  fluctuating  head, 

Fig.   87 263 

Design  of  power-house  foundation 254 

Design  of  power  house  for  high  head,  Fig. 

89  267 

Design  of  power  house  for  low  head,  Figs. 

84-86-88 259-262,  265 

Design    of   power   house   for   medium   head, 

Fig.   89 267 

Design  of  power  house,  submerged 266 

Design  of  power-house  substructure 255 

Design  of  power-house  superstructure 256 

Design  of  reaction  turbine,  Figs.  109,  110. 

291,  293 

Design  of  reaction  turbine,  theory 318 

Design  of  sluice 201 

Design  for  solid  spillway  apron 186 

Design    for    solid    spillway,    characteristics, 

Table  107 185 

Design  for  solid  spillway  crest 185 

Design  for  solid  spillway,  practical 180 

Design  for  solid  spillway,  theoretical 176 

Design  for  solid  spillway  toe 186 

Design  of  stop-log  section,  theory 201 

Design  of  timber  spillway,  analysis  of 206 

Design    of    vertical    turbines,    paired    and 

drowned,  Fig.  115 302 

Design    of    vertical    turbines,    paired    and 

cased,  Fig.  116 305 

Designing  and  constructing  the  plant 90 

Development  cost 61-74 

Development  programme,  direct 116 


PAGE 

Development  programme,  distant 117 

Development  programme,  scope 129 

Development  programme,  short  diversion.  .  .  117 

Dike,  description  of 135 

Dike,  sheet  pile,  description  of 142 

Dike,  steel  pile,  description  of 142 

Dimensions  for  concrete-steel  beams,  Table  7  141 

Dimensions  of  dams,  masonry,  Diagram  9 .  .  63 

Dimensions  of  generators,  Diagram  40 357 

Dimensions  of  gravity  spillways,  Table  12.  .  192 
Dimensions    of    horizontal    turbines,    cased, 

Diagram  37 317 

Dimensions  of  horizontal  turbines,  drowned, 

Diagram  35 307 

Dimensions    of    single    horizontal    turbine, 

drowned,  Diagram  36 311 

Dimensions  of  solid  spillways,  Table  10. ...  185 

Dimensions  of  .turbine  draft  tubes 319 

Dimensions  of  turbine  guide-wheel  openings  319 

Dimensions  of  turbine  runners,  theory 318 

Dimensions  of  turbine  runners  vent  area.  . .  318 

Direct  development  programme 116 

Discharge,  central  reaction  turbine,  descrip- 
tion of 294 

Discharge  curve  of  stream 103 

Discharge  curve  of  stream,  Diagram  19.  ...  106 

Diversion  programme,  distant 117 

Diversion  programme,  short 117 

Diversion  works 235 

Diversion  works,  cost  of 67 

Draft  tube,  turbine,  dimensions 319 

Draft  tube,  turbine,  theory  of 296 

Drainage  area,  characteristics Ill 

Drainage  area,  definition 9 

Drainage  area,  geology  of 27 

Drainage  areas  of  rivers,  Table  1 10 

Drainage  areas,  topography  of 26 

Dynamic  energy,  definition 276-277 

Dynamo    armatures 340 

Dynamo  commutators,  collectors 341 

Dynamo,  continuous  current 337 

Dynamo  excitation 338-341 

Dynamo  field 341 

Dynamo  parts,  description 337 

Dynamo  poles,  definition 337 

Dynamo  winding 338-340 

Earth  embankments,  quantities,  Diagram  14     71 

Earth  and  rockfill  dams 222 

Earth  and  rockfill  excavation  from  canal .  .  .   243 
Efficiencies,  maximum,  of  impulse  wheel,  out- 
put, Diagram  39 323 


376 


GENERAL   INDEX 


Efficiencies,    maximum,    of    impulse    wheel, 

theory   320 

Efficiencies,  maximum,  output  constants  of 

all   turbines 322 

Efficiencies,   maximum,   of   reaction   turbine 

output,  Diagram  38 319 

Efficiencies  of  turbines,  theory  of 298 

Electric  equipment 330 

Electric  generating  plant,  character  of 350 

Electric  and  water  power,  Diagram  3 43 

Electro-motive  force 330-331 

Electro-motive  force,  magnitude  of 333 

Elevations     (survey) 93 

Embankments,  reservoir,  cost  of 68 

Embankments,    reservoir,    quantities,    Dia- 
gram  14 71 

Energy,  dynamic,  definition  of 276 

Energy,  hydro-dynamic,  definition  of 276 

Energy,  mechanical,  defined 276 

Energy  of  water 276 

Engineering  control  of  construction 371 

Equipment,   electric 330 

Equipment,  hydraulic,  theory 276 

Equipment,  power 276 

Equipment,  power,  general  cost  of 70 

Equipment  of  transmission  plant 358 

Equipment,  turbine,  determination  of 322 

Estimates  of  plant, 369 

Evaporation,  definition 9 

Evaporation  and  precipitation,  flow  deduced 

from 108 

Evaporation  records 34-109 

Examinations  of  maps 90 

Excavation  of  earth  and  rock  from  canals . . 

242-243 

Excavation  quantity  for  canal  prisms 243 

Excitation  of  dynamos,  definition 338-341 

Fall,  available 40 

Feasibility  of  hydro-electric  project 47 

Field,  dynamo,  description 341 

Fishladders,  design  of 231 

Fixed  charges  of  plants,  500-1000  H.  P., 

Diagram  5 57 

Fixed  charges  of  plants,  1000-5000  H.P., 

Diagram  6 58 

Fixed  charges  of  plants,  5000-10,000  H.  P., 

Diagram  7 59 

Flashboards,  design  of 231 

Floats,  surface,  subsurface,  and  rod 102 

Flood  flow,  determination  of 159 

Flora  and  culture  of  drainage  area 28 


PAGE 

Flow  deduced  from  precipitation  and  evap- 
oration    108 

Flow  deductions 36 

Flow,  definition  of 8 

Flow,  determination,  Ex 109 

Flow  over  flat-crested  weirs,  Diagram  2 ....  39 

Flow,  flood,  determination  of 159 

Flow,  low  monthly,  of  rivers,  Table  1 10 

Flow  measurements 37 

Flow  measurements  by  weir,  Fig.  11 107 

Flow  measurements,   rod   to  mean  velocity, 

Diagram   18 105 

Flow  measurements,  surface  to  mean  veloc- 
ity, Diagram  17 104 

Flow  in  open  channels,  constants,  Tables  16- 

24 238-241 

Flow  in  open  channels,  theory 236 

Flow  through  overflow  sluice,  theory  of.  ...  195 
Flow  in  pipes,  constants,  Tables  25-29.   249-251 

Flow  in  pipes,  discharge  volume,  Table  26.  .  249 

Flow  in  pipes,  theory 249 

Flow  in  pipes,  velocity  of,  Tables  27-29  250-251 

Flow,  power,  definition 41 

Flow  from  reservoirs,  Diagram  4 45 

Flow,  stream,  deductions 36 

Flow,  stream,  determination 30 

Flow  through  turbines,  definition 287 

Flow  through  turbines,  theory  of 278 

Flumes,  diversion 246 

Flux,  magnetic,  density 331 

Forebay 246 

Forms,  concrete,  definition 140 

Foundation  floor,  description  of 148 

Foundation  of  power  house 254 

Foundations,  dam,  functions  of 131 

Foundations,  design 144-147 

Foundations,  quantities  for,  Diagram  12 ...  66 

Frequencies  of  current 335 

Galleries  through  spillways 235 

Gate,  cylinder,  of  turbine 289 

Gate,  register,  of  turbine 289 

Gates,    described 198 

Gates,  operation 230 

Gates,  reaction  turbines 289 

Gate  valve 252 

Gauge,  B.  &  S.   (Brown  &  Sharpe),  of  wire, 

Table  31 340 

Gaugings  of  stream,  Figs.  9  and  10.  ...    100-102 

Generator,  dimensions  of,  Diagram  40 357 

Generator,  how  driven,  determined 354 

Generator    (see  Dynamo) 


GENERAL   INDEX 


377 


PAGE 

Generator,  standard  sizes,  Table  32 355 

Generator,  type  of,  determined 354 

Generator,  units,  determined 354 

Geology  of  drainage  area 27 

Gneiss,  characteristics  of 131 

Governing  tangential  impulse  wheels 320 

Government  control  over  rivers 47,  50 

Governors,  turbine 326 

Governors,  turbine,  Lombard 327 

Governors,   turbine,   Lombard-Replogle 328 

Governors,  turbine,  Sturgess 327 

Governors,  turbine,  Woodward 328 

Gradient,  hydraulic,  definition 251 

Granite,  characteristics  of 131 

Gravel,  characteristics  of 133 

Gravity  spillway,  design  of,  Table  10-14  191-194 

Gravity  spillway,  theory  of 187 

Ground    detectors 349 

Ground  flow  diagrams 113 

Ground  storage,  definition Ill 

Ground  water,  definition 8 

Guard  wires 350 

Guide  passages  of  reaction  turbine,  described  289 
Guide  passages  of  reaction  turbine,  dimen- 
sions     319 

Guide  vanes  of  reaction  turbine,  described.  .   289 
Guide  wheel  of  reaction  turbine,  described .  .   289 

Headgates  of  canal 246 

Height  of  dam,  analyzed 149 

Horizontal  turbines,  cased,  described 310 

Horizontal  turbines,  cased,  dimensions 317 

Horizontal  turbines,  drowned,  described....  304 
Horizontal    turbines,    drowned,    dimensions, 

Diagram   35 307 

Horizontal  turbines,  four,  drowned,  design, 

Fig.  119 312 

Horizontal   turbines,  paired  and  cased,  de- 
sign, Fig.  120 313 

Horizontal   turbines,  paired  and  cased,  de- 
sign, Fig.   121 315 

Horizontal  turbines,  single  drowned,  dimen- 
sions, Diagram  36 311 

Horizontal  turbines,  three  drowned,  design, 

Fig.    118 309 

Horse-power,  definition 8 

Horse-power,  electric 8 

Horse-power  and  kilowatt,  Diagram  1 3 

Horse-power  and  kilowatt  rates,  Diagram  8.      60 

Hydraulic  equipment,  theory 276 

Hydraulic-fill  dam 226 

Hydraulic  gradient,  definition 251 


PAGE 

Hydraulic  losses  of  energy  in  turbines 299 

Hydraulic  radius,  definition. 237 

Hydraulic  radius  of  pipes,  Table  25 249 

Hydraulic  relief  valves 330 

Hydro-dynamic  energy,  definition 276-277 

Hydro-electric  project,  analysis  of 1 

Ice  fenders,  design  of 231 

Impedance  in  current,  definition 236 

Impulse,  definition 276 

Impulse  turbine,  defined 286 

Impulse  turbine,  description 296 

Impulse  wheel,  design  of,  Fig.  114 297 

Impulse  wheel,  governing 329 

Impulse  wheel,  maximum  efficiency  output, 

Diagram  39 323 

Impulse  wheel,  output,  theory 320 

Incandescent  light  service 2 

Inductance,  current,  definition  of 335-347 

Installations,  turbine,  typical 300 

Insulator  pins,  transmission  line 361 

Insulators,   transmission   line 361 

Intake  to  canal 246 

Investment  balance,  Ex 55 

Kilowatts  and  horse-power,  Diagram  1 3 

Kilowatts     and     horse-power     rates,     Dia- 
gram   8 60 

Kinetic  energy  of  water 276-277 

Lease  from  War  Department 48 

Length  of  spillway,  analyzed 159 

Levels    ( survey ) 93 

License  from  War  Department 49 

Lighting,  current  service 1 

Lighting,  power  for,  Diagram  1 3 

Lightning  arresters 349 

Lights,  arc 1 

Lights,    incandescent 2 

Limestones,  characteristics  of 132 

Lining  of  canal  bed  and  sides 244 

Loam,  characteristics  of 133 

Location  of  canal ; . .  242 

Location  of  pipe  line 251 

Location  of  power  house ." 254 

Log  chutes 2,30 

Log  cribs,  description  of 136 

Lombard   governor 327 

Lombard-Replogle   governor 328 

Losses  of  energy  in  turbines 299-300 

Magnet,  field,  conductor,  size  of 339 


378 


GENERAL   INDEX 


Magnet,  field,  section  of 339 

Magnetic  field 330 

Magnetic  flux 330-331 

Magnetic  lines 331 

Magneto-dynamic  theory 330 

Magneto-electric  units 331 

Magnets,  permeability  of,  Table  30 339 

Maps,  examination  of 90 

Market,  current,  analysis  of 4 

Market,  current,  canvass 5 

Market  for  electric  current 1 

Marl,  characteristics  of 133 

Mean  and  rod  velocity,  Diagram  18 105 

Mean  and  surface  velocity,  Diagram  17 ....  104 

Mechanical  energy,  defined 276 

Mechanical  losses  of  energy  in  turbines .  299-300 

Mixing  concrete,  description  of 140 

Moment  of  moving  water,  defined 278 

Moment,  pressure,  retaining  walls,  Diagrams 

31-33  215-217 

Moment,  pressure,  solid  spillways,  Diagrams 

26-29 165-168 

Monolithic  concrete,  definition  of 140 

Monophase  current,  definition 335-342 

Motor  generator,  description 342 

Movable  weir,  described 198 

Mud,  characteristics  of 133 

Needles,    described 197 

Ohm,    definition 331 

Open  channels,  flow  in,  theory  of 236 

Open  channels,  slope,  Tables  16-19 238-239 

Open  channels,  velocity,  Tables  20-24..  240-241 

Open  spillway,  description  of 194 

Orifices,  submerged,  discharge  theory 195 

Output  of  impulse  turbine,  theory  of 320 

Oiitput    of    impulse    wheel,    maximum    effi- 
ciency, Diagram  39 323 

Output  of  maximum  efficiency,  constants  for 

all   turbines 320 

Output,  power,  definition 40 

Output  of  reaction  turbine,  theory  of 314 

Output  of  reaction  turbines,  maximum  effi- 
ciency, Diagram  38 319 

Overflow  sluice,  described 196 

Overflow  sluice,  discharge,  theory  of 195 

Overturning  of  spillway,  theory  of 170 

Paving,  description  of 142 

Peat,  characteristics  of 133 

Perimeter,  coefficient  of  roughness 103 


PAGE 

Perimeter  of  channel,  definition 236 

Perimeter  of  channel,  roughness  coefficient.   237 

Permeability  of  magnets,  Table  30 339 

Phase,  current,  definition  of 335 

Phase   indicators 349 

Phasemeters     349 

Phase  transformer,  definition 342 

Phototopographic  survey,  Figs.  3  to  6 ....    94-97 

Pile,  sheet,  dike,  description  of 142 

Pile,  steel,  dike,  description  of 142 

Piles,  bearing  capacity 138 

Piles,  bearing,  description  of 138 

Piles,  concrete,  description  of 138 

Pilot   lamps 349 

Pins,  insulator,  for  transmission  line 361 

Pipe  areas,  Table  25 248 

Pipe,  concrete-steel,  cost  of 67 

Pipe,  diversion,  location  of 251 

Pipe,  recommendable  size  of. 252 

Pipe,  steel  plate,  cost  of 67 

Pipe,  wood  stave,  cost  of 67 

Pipes,  discharge,  volume  of,  Table  26 248 

Pipes,  flow  in,  constants  for,  Tables  25-29 .  . 

248-251 

Pipes,  flow  in,  theory 248 

Plans  for  construction 368 

Platform,  operating 230 

Poles  of  dynamos,  definition 337 

Poles  for  transmission  line 358 

Polyphase  current,  definition 335-342 

Pondage,  definition 41 

Portland  cement,  specifications  of 139 

Potential  energy  of  water 276-277 

Power  auxiliary,  definition 42 

Power  equipment 276 

Power  flow 41 

Power  house,  appurtenances 264 

Power  house,  equipment,  general  cost 70 

Power  house  for  fluctuating  head,  Fig.  87 .  .   263 

Power  house,  foundation 254 

Power  house,  general 67 

Power  house  for  high  head,  Fig.  89 267 

Power  house,  location 254 

Power  house  for  low  head,  Figs.  84-86,  88 . . 

259-262,  265 

Power  house  for  medium  head,  Fig.  89 267 

Power  house,  quantities,  Diagram  13 69 

Power  house,  submerged,  design 266 

Power  house,  substructure 255 

Power,  lighting,  Diagram  1 3 

Power  opportunity 8 

Power  output,  definition 40 


GENERAL   INDEX 


379 


PAGE 

Power  plant,  auxiliary 364 

Power  required  to  operate  turbine  gates.  .  .  .    329 

Power,  water  and  electric,  Diagram  3 43 

Practicability  of  hydro-electric  project...   47-54 

Precipitation,  definition 8 

Precipitation  and  evaporation,  flow  deduced 

from  108 

Precipitation  profiles 35 

Precipitation  records 28 

Presentation  of  project 75 

Pressure  moments  on  retaining  walls,  Dia- 
grams 31-33 215-217 

Pressure  moments   in   solid   spillways,   Dia- 
grams 26-29 165-168 

Pressure  and  resistance,  theory  of 160 

Privileges    (see  Control,  Title) 

Puddle,  definition 139 


Quantities 
Quantities 
Quantities 
Quantities 

10 

Quantities 

Diagram 
Quantities 
Quantities 
Quantities 

Diagram 
Quantities 
Quantities 
Quantities 
Quantities 
Quicksand, 


for  coffer  structures,  Table  8.  ...    144 

for  cut-off  walls,  Table  9 147 

for  dam  abutments,  Diagram  12.      66 
for  dam,  concrete-steel,  Diagram 


64 


for 
14. 


dam,    earth    embankments, 


for  dam  foundations,  Diagram  12     66 
for  dam  masonry,  Diagram  9 ...      63 
for    dam,    reservoir    bulkheads, 

15 72 

of  excavation  from  canal  prisms.  243 
for  gravity  spillway,  Table  13.  ..  192 
for  power  house,  Diagram  13.  ..  69 

for  timber  spillway,  Table  15 208 

characteristics   of .  .  .133 


Rack,  trash,  for  pipe  intakes 252 

Eadius,  hydraulic,  definition 249 

Rates,  current,  H.  P.  and  K.  W.,  Diagram  8.  60 

Reactance,  current,  definition  of 336 

Reaction,  current,  definition  of 335 

Reaction,   definition 276 

Reaction  turbine  case 292 

Reaction  turbine,  central  discharge,  descrip- 
tion of 294 

Reaction  turbine,  defined 286 

Reaction  turbine,  design,  Figs.   109,  110... 

291,  293 

Reaction  turbine,  design,  theory 318 

Reaction  turbine,  gates  of 289 

Reaction  turbine,  guide  wheel,  described...  289 
Reaction   turbine,   maximum   efficiency   out- 
put. Diagram  38 319 


PAGE 

Reaction  turbine,  mixed  flow,  described ....  287 

Reaction  turbine  output,  theory  of 314 

Reaction  turbine  runner,  described 287 

Reconnaissance 91 

Records  of  evaporation 33 

Records  of  precipitation 28 

Records  of  precipitation,  Ex 31 

Register  gate  of  turbine 289 

Reinforcing  steel,  characteristics  of,  Table  5  144 

Report  on  hydro-electric  project,  Ex 75 

Reservoir  bulkheads,  quantities,  Diagram  15  72 

Reservoir   dams,  described 221 

Reservoir  embankments,  cost  of 68 

Reservoir,  flow  from,  Diagram  4 45 

Reservoir    sites 115 

Reservoir  storage,  value  of 44 

Resistance  of  aluminum  wire,  Table  33 350 

Resistance  of  copper  wire,  Table  31 340 

Resistance  and  pressure,  theory  of 160 

Retaining  wall,   concrete-steel,   described.  .  .  214 
Retaining  wall,  pressure  moments,  Diagrams 

31-33   215-217 

Retaining  wall,  theory  of 210 

Rheostat,  described 350 

Rights    (see  Control,  Title) 

Riparian  title 53 

Riprap,  description  of 142 

Rock,   characteristics  of 131 

Rock,  drilling 242 

Rock  and  earth  excavation  from  canals.   242-243 

Rock  and  earth  fill  dams 222 

Rod  floats,  stream  gauging 102 

Rod  to  mean  velocity,  Diagram  18 105 

Rotary  converter,  description 342 

Roughness  of  perimeter,  coefficient 103-237 

Runner  of  reaction  turbine,  described 287 

Runner  of  reaction  turbine,  vent  areas 318 

Run-off,   monthly,   profile 35 

Run-off,  ordinary  dry  year,  Ex 114 

Run-off,  storm,  definition 8 

Safety  factor  for  spillway 174 

Safety  factor  for  transmission  line 360 

Sand,  characteristics  of 133 

Sand  for  earth  dam 226 

Sand,  specifications  of 139 

Sandstone,  characteristics  of 132 

Self-induction  current,  definition 335 

Series  winding  of  field  magnets 338 

Service,  current,  industrial 2 

Service,  current,  lighting 1 

Service,  current,  special 2 


380 


GENERAL   INDEX 


PAGE 

Service,  current,  traction 4 

Sheet  pile  dike,  description  of 142 

Sheet,  steel,  description  of 136 

Sheet,  timber,  description  of 136 

Short  diversion  programme 117 

Shunt  winding  of  field  magnets 338 

Shutters,    described 198 

Sienite,  characteristics  of 131 

Silt,  characteristics  of 133 

Single  phase  current,  definition 335 

Sliding  of  spillways,  theory 169 

Slip  rings,  dynamo 342 

Slope  of  backswell  above  dam 149 

Slope  of  backswell,  Diagrams  20-25 ....   152-156 

Slope  in  curved  channels 242 

Slope  in  open  channels,  Tables  16-19.  .  .   238-239 

Sluice  design 201 

Sluice,  overflow,  described 196 

Sluice,  overflow,  theory  of  discharge  through  195 

Sluice,  underflow,  design 230 

Soil,  characteristics  of 133 

Span,  length  of  transmission 359 

Specifications  for  construction 369 

Speed  of  standard  generators,  Table  32 355 

Spillway  abutments,  quantities  for,  Diagram 

12  66 

Spillway  air  vents 235 

Spillway  apron,  shaping,  theory 186 

Spillway,  concrete-steel,  quantities  for,  Dia- 
gram   10 64 

Spillway  crest,  shaping,  theory 185 

Spillway  crushing,  theory  of 170 

Spillway  and  dam  appurtenances 227 

Spillway  foundation 131,  144,  147 

Spillway    foundation,    quantities    for,    Dia- 
gram   12 66 

Spillway  galleries 235 

Spillway,  gravity,  design,  characteristics  of, 

Table  14 194 

Spillway,  gravity,  design  of,  Tables  11-14.  . 

191-194 

Spillway,  gravity  type,  theory 187 

Spillway,  height  of. 149 

Spillway,  length  of 159 

Spillway,     masonry,     quantities     for,     Dia- 
gram  9 63 

Spillway,  open,  description  of 194 

Spillway,  pressure  and  resistance,  theory  of  160 

Spillway,  safety  factor  for 174 

Spillway  sliding,  theory  of 169 

Spillway,  solid,  design  characteristics,  Table 

10  ..                         185 


PAGE 

Spillway,  solid,  practical  design 180 

Spillway,  solid,  pressure  moments,  Diagrams 

26-29  165-168 

Spillway,  solid,  theoretical  design 176 

Spillway  superstructure 148 

Spillway,  timber  and  concrete,  comparative 

cost,  Diagram  30 211 

Spillway,  timber,  described 205 

Spillway,  timber,  design,  analysis  of 206 

Spillway,  timber,  quantities  for,  Table  15..  208 

Spillway  toe,  shaping,  theory 186 

Spillway  wells 235 

Stand  pipes 330 

State  control  of  rivers 53 

Static  transformers 343 

Steel  concrete,  definition  of 140 

Steel  concrete  beams,  constants  of,  Table  6.  141 

Steel  concrete  beams,  Table  7 141 

Steel  curtain,  description  of 139 

Steel  pile  dike,  description  of 142 

Steel  plate  pipe,  cost  of 67 

Steel,  reinforcing,  characteristic  of,  Table  5.  141 

Steel  sheet,  description  of 136 

Stop-logs,  described 196 

Stop-logs,  section,  theory 201 

Storage  battery,  described 366 

Storage,  definition 42 

Storage,  ground,  definition Ill 

Storage,  ground,  depletion 112 

Storage  reservoir,  value  of 44 

Storm  run-off,  definition 8 

Stream  discharge  curve 103 

Stream  discharge  curve,  Ex.,  Diagram  19 .  .  106 

Stream  flow,  determination  of 30- 

Stream  gaugings,  Figs.  9  and  10 100-102 

Stream  gaugings,  reductions 103 

Structural  types 131 

Sturgess  governor 327 

Submerged  orifice,  theory  of  discharge 

through 227 

Submerged  power  house,  design  of 266 

Substation 364 

Substation,  general  cost  of 70 

Subsurface  floats,  stream  gauging 102 

Superstructure  of  dam,  description  of 148 

Superstructure  of  power  house 255-264 

Surface  floats,  stream  gauging 102 

Surface  to  mean  velocity,.Diagram  17 104 

Survey  90 

Switchboard  348 

Switches  349 

Synchronizers  (see  Phase  indicators) ......  349- 


GENERAL    INDEX 


381 


PAGE 

Theory  of  crushing  of  Spillway 170 

Theory  of  current  transmission 345 

Theory  of  deducting  turbine  efficiencies ....  298 

Theory  of  design  of  reaction  turbine 318 

Theory  for  design  of  stop-log  section 201 

Theory  for  design  of  timber  spillway 206 

Theory  of  discharge  through  overflow  sluice .  195 
Theory  of  discharge  through  submerged  ori- 
fices      227 

Theory  of  flow  in  open  channels 236 

Theory  of  flow  in  pipes 249 

Theory  of  flow  through  turbines 278 

Theory  of  gravity  spillway 187 

Theory  of  hydraulic  equipment 276 

Theory  of  impulse  wheel  output 320 

Theory  of  magneto-dynamic  energy 330 

Theory  of  overturning  of  spillway 170 

Theory  of  pressure  and  resistance 160 

Theory  of  reaction  turbine  output 314 

Theory  of  retaining  wall  design 210 

Theory  of  shaping  spillway  apron 186 

Theory  of  shaping  spillway  crest. 185 

Theory  of  shaping  spillway  toe 186 

Theory  of  sliding  of  spillway 169 

Theory  of  solid  spillway  design 176 

Theory  of  static  transformers 344 

Theory  of  transmission  line  span  length. .  . .  360 

Theory  of  turbine  draft  tube  effect 296 

Theory  of  weir  flow  measurement 107 

Three-phase  current,  definition • 335 

Timber  and  concrete  spillways,  comparative 

cost,  Diagram  30 211 

Timber  cribs,  description  of 137 

Timber  curtain,  description  of 139 

Timber,  definition  of  terms 137 

Timber  sheet,  description  of 136 

Timber  spillway,  description  of 205 

Timber  spillway,  design,  analysis 206 

Timber  spillway,  quantities  for,  Table  15..  208 

Title,   riparian 53 

Toe  of  solid  spillway,  shape  of 186 

Topography  of  drainage  area 26 

Topography  ( survey) 94 

Traction  current  service 4 

Transformers,   cost  of 70 

Transformers,  static 343 

Transmission  of  continuous  current 346 

Transmission  of  current 345 

Transmission,  general  cost  of 70 

Transmission  line  conductors 358 

Transmission  line  fastenings 358 

Transmission  line  supports 358 


PAGE 
Transmission  line  wire,  weight,  Diagram  16     73 

Transmission  plant   equipment 358 

Trash  rack  for  pipe  intake 252 

Trenching  for  cut-off 146 

Triangulation  92 

Tripod  and  target  (survey),  Fig.  2 93 

Turbine,  central  discharge,  design  of 295 

Turbine  draft  tubes,  dimensions 319 

Turbine  draft  tube,  theory  of 296 

Turbine  efficiencies,  theory  of 298 

Turbine  equipment,  determination  of 322 

Turbine,  flow  through,  definition  of 287 

Turbine,  flow  through,  theory  of 278 

Turbine  gates,  power  required  to  operate.  . .   329 

Turbine  governor 326 

Turbine  governor,  Lombard 327 

Turbine  gorernor,  Lombard-Replogle 328 

Turbine  governor,  Sturgess 327 

Turbine  governor,  Woodward 328 

Turbine  guide-wheel  openings,  dimensions..   319 

Turbine,  horizontal  cased,  described 310 

Turbine,  horizontal  cased,  dimensions,  Dia- 
gram  37 317 

Turbine,  horizontal  drowned,  described 304 

Turbine,    horizontal    drowned,    dimensions, 

Diameter  35 307 

Turbine,   horizontal,   four   drowned,   design, 

Fig.    119 312 

Turbine,   horizontal,   paired   and   cased,   de- 
sign, Figs.  120,  121 313,  315 

Turbine,  horizontal,  paired  and  drowned,  de- 
sign, Fig.  117 306 

Turbine,  horizontal,  single,  drowned,  dimen- 
sions, Diagram  36 311 

Turbine,  horizontal,  three  drowned,  design, 

Fig.    118 309 

Turbine,  impulse 286 

Turbine,   impulse,  description 296 

Turbine,  impulse,  design  of,  Fig.  114 297 

Turbine  installations,  typical 300 

Turbine,  losses  of  energy  in 299-300 

Turbine,    reaction 286 

Turbine,  reaction,  case 292 

Turbine,  reaction,  central  discharge,  descrip- 
tion of ' 294 

Turbine,  reaction,  design  of,  Figs.  109,  110. 

291,  293 

Turbine,  reaction,  design  of,  theory 318 

Turbine,  reaction,  gates 289 

Turbine,  reaction,  guide  wheel,  described...   289 
Turbine,   reaction,  maximum   efficiency  out- 
put, Diagram  38 319 


382 


GENERAL   INDEX 


PAGE 

Turbine,  reaction,  mixed  flow,  described ....   287 

Turbine,  reaction,  output,  theory  of 314 

Turbine  runner,  dimensions 318 

Turbine,  tangential  impulse,  maximum  effi- 
ciency output,  Diagram  39 323 

Turbine,  vertical,  cased,  described 304 

Turbine,    vertical,    cased,    dimensions,    Dia- 
gram 34 303 

Turbine,  vertical,  paired  and  cased,  design, 

Fig.    116 305 

Turbine,  vertical,  paired  and  drowned,   de- 
sign, Fig.   115 302 

Turbines,   classification  of 285 

Two-phase  current,  definition 335 

Underflow  sluice,  design  of 230 

Value  of  project 75 

Valve  gate 252 

Valves,  described 197 

Valves,  hydraulic  relief 330 

Vanes,  guide,  of  reaction  turbines 289 

Velocity  in  open  channels,  Tables  20-24,  240-241 

Velocity  in  pipes,  Tables  27-29 250-251 

Velocity,  rod  to  mean,  Diagram  18 105 

Velocity,  surface  to  mean,  Diagram  17 1"04 

Vents,  air,  in  spillways 235 

Vertical  turbine  cased,  described 304 

Vertical  turbine  cased,  dimensions,  Diagram 

34  303 

Vertical  turbine  drowned,  described 301 

Vertical   turbine  paired   and  cased,   design, 

Fig.    116 305 

Vertical    turbine   paired    and    drowned,    de- 
sign, Fig.  115 302 

Volt,  definition  of 331 

Voltage  drop  (loss) 346 

Voltage  of  standard  generators,  Table  32 . .  355 


PAGE 

Voltaic  electricity 330 

Wall,  core,  description  of 139 

Wall,  cut-off,  description  of 139 

Wall,  cut-off,  quantities  for,  Table  9 147 

War  Department,  control  of  rivers,  Table  3.  50 

War  Department,  lease  from 48 

War  Department,  license  from 49 

Waste  weir  in  canals 246 

Water  power  and  electric  power,  Diagram  3  43 

Water-shed,  definition 9 

Watt,  definition  of 331 

Wattless  current,  definition 336 

Wattmeters,  described 349 

Weight  of  aluminum  wire,  Table  33 359 

Weight  of  copper  wire,  Table  31 340 

Weight  of  transmission  line  wire,  Diagram 

16  73 

Weir,  flow  over  flat-crested,  Diagram  2 39 

Weir,  flow  measurement,  Fig.  11 107 

Weir,  movable,  described 198 

Weir,  waste,  in  canals 248 

Wells  in  spillways 235 

Wicket  gate  of  reaction  turbine 289 

Winding  of  armature,  described 340 

Winding,  compound,  of  field  magnets 338 

Winding,  series,  of  field  magnets 338 

Winding,  shunt,  of  field  magnets 338 

Wire,  aluminum 346 

Wire,  aluminum,  characteristics  of,  Table  33  359 

Wire,  copper,  characteristics  of,  Table  31.  ..  340 

Wire  formula 340 

Wire  gauge,  B.  &  S.  (Brown  &  Sharpe), 

Table  31 340 

Wire,  transmission  line,  weight  of,  Diagram 

16  73 

Wood-stave  pipe,  cost  of 67 

Woodward  governor 328 


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